History

Merge tag 'i2c-for-6.13-rc1-part3' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux

Pull i2c component probing support from Wolfram Sang: "Add OF component probing. Some devices are designed and manufactured with some components having multiple drop-in replacement options. These components are often connected to the mainboard via ribbon cables, having the same signals and pin assignments across all options. These may include the display panel and touchscreen on laptops and tablets, and the trackpad on laptops. Sometimes which component option is used in a particular device can be detected by some firmware provided identifier, other times that information is not available, and the kernel has to try to probe each device. Instead of a delicate dance between drivers and device tree quirks, this change introduces a simple I2C component probe function. For a given class of devices on the same I2C bus, it will go through all of them, doing a simple I2C read transfer and see which one of them responds. It will then enable the device that responds" * tag 'i2c-for-6.13-rc1-part3' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux: MAINTAINERS: fix typo in I2C OF COMPONENT PROBER of: base: Document prefix argument for of_get_next_child_with_prefix() i2c: Fix whitespace style issue arm64: dts: mediatek: mt8173-elm-hana: Mark touchscreens and trackpads as fail platform/chrome: Introduce device tree hardware prober i2c: of-prober: Add GPIO support to simple helpers i2c: of-prober: Add simple helpers for regulator support i2c: Introduce OF component probe function of: base: Add for_each_child_of_node_with_prefix() of: dynamic: Add of_changeset_update_prop_string

Linus Torvalds committed 1 year ago

Commit a14bf462 parents 88862ee caf4bdb13 files · +840 −3Browse files

Unified · Split

13 files
  1. MAINTAINERS +8 −0
  2. arch/arm64/boot/dts/mediatek/mt8173-elm-hana.dtsi +14 −0
  3. arch/arm64/boot/dts/mediatek/mt8173-elm.dtsi +2 −2
  4. drivers/i2c/Makefile +1 −0
  5. drivers/i2c/i2c-core-of-prober.c +415 −0
  6. drivers/i2c/i2c-core-smbus.c +1 −1
  7. drivers/of/base.c +36 −0
  8. drivers/of/dynamic.c +44 −0
  9. drivers/platform/chrome/Kconfig +11 −0
  10. drivers/platform/chrome/Makefile +1 −0
  11. drivers/platform/chrome/chromeos_of_hw_prober.c +154 −0
  12. include/linux/i2c-of-prober.h +140 −0
  13. include/linux/of.h +13 −0
MAINTAINERS+8−0
@@ -10758,6 +10758,14 @@ S: Maintained · 10757 unmodified lines
1075810758 F: Documentation/devicetree/bindings/i2c/marvell,mv64xxx-i2c.yaml
1075910759 F: drivers/i2c/busses/i2c-mv64xxx.c
1076010760
10761+I2C OF COMPONENT PROBER
10762+M: Chen-Yu Tsai <wenst@chromium.org>
10763+L: linux-i2c@vger.kernel.org
10764+L: devicetree@vger.kernel.org
10765+S: Maintained
10766+F: drivers/i2c/i2c-core-of-prober.c
10767+F: include/linux/i2c-of-prober.h
10768+
1076110769 I2C OVER PARALLEL PORT
1076210770 M: Jean Delvare <jdelvare@suse.com>
1076310771 L: linux-i2c@vger.kernel.org
arch/arm64/boot/dts/mediatek/mt8173-elm-hana.dtsi+14−0
@@ -14,6 +14,7 @@ · 13 unmodified lines
1414 compatible = "melfas,mip4_ts";
1515 reg = <0x34>;
1616 interrupts-extended = <&pio 88 IRQ_TYPE_LEVEL_LOW>;
17+ status = "fail-needs-probe";
1718 };
1819
1920 /*
@@ -26,6 +27,7 @@ · 6 unmodified lines
2627 reg = <0x20>;
2728 hid-descr-addr = <0x0020>;
2829 interrupts-extended = <&pio 88 IRQ_TYPE_LEVEL_LOW>;
30+ status = "fail-needs-probe";
2931 };
3032
3133 /* Lenovo Ideapad C330 uses G2Touch touchscreen as a 2nd source touchscreen */
@@ -35,6 +37,7 @@ · 3 unmodified lines
3537 hid-descr-addr = <0x0001>;
3638 interrupt-parent = <&pio>;
3739 interrupts = <88 IRQ_TYPE_LEVEL_LOW>;
40+ status = "fail-needs-probe";
3841 };
3942 };
4043
@@ -47,6 +50,8 @@ · 6 unmodified lines
4750 trackpad2: trackpad@2c {
4851 compatible = "hid-over-i2c";
4952 interrupts-extended = <&pio 117 IRQ_TYPE_LEVEL_LOW>;
53+ pinctrl-names = "default";
54+ pinctrl-0 = <&trackpad_irq>;
5055 reg = <0x2c>;
5156 hid-descr-addr = <0x0020>;
5257 /*
@@ -58,6 +63,7 @@ · 5 unmodified lines
5863 */
5964 vdd-supply = <&mt6397_vgp6_reg>;
6065 wakeup-source;
66+ status = "fail-needs-probe";
6167 };
6268 };
6369
@@ -82,3 +88,11 @@ · 18 unmodified lines
8288 };
8389 };
8490 };
91+
92+&touchscreen {
93+ status = "fail-needs-probe";
94+};
95+
96+&trackpad {
97+ status = "fail-needs-probe";
98+};
arch/arm64/boot/dts/mediatek/mt8173-elm.dtsi+2−2
@@ -358,12 +358,12 @@ · 357 unmodified lines
358358 &i2c4 {
359359 clock-frequency = <400000>;
360360 status = "okay";
361− pinctrl-names = "default";
362− pinctrl-0 = <&trackpad_irq>;
363361
364362 trackpad: trackpad@15 {
365363 compatible = "elan,ekth3000";
366364 interrupts-extended = <&pio 117 IRQ_TYPE_LEVEL_LOW>;
365+ pinctrl-names = "default";
366+ pinctrl-0 = <&trackpad_irq>;
367367 reg = <0x15>;
368368 vcc-supply = <&mt6397_vgp6_reg>;
369369 wakeup-source;
drivers/i2c/Makefile+1−0
@@ -9,6 +9,7 @@ i2c-core-y := i2c-core-base.o i2c-core-smbus.o · 8 unmodified lines
99 i2c-core-$(CONFIG_ACPI) += i2c-core-acpi.o
1010 i2c-core-$(CONFIG_I2C_SLAVE) += i2c-core-slave.o
1111 i2c-core-$(CONFIG_OF) += i2c-core-of.o
12+i2c-core-$(CONFIG_OF_DYNAMIC) += i2c-core-of-prober.o
1213
1314 obj-$(CONFIG_I2C_SMBUS) += i2c-smbus.o
1415 obj-$(CONFIG_I2C_CHARDEV) += i2c-dev.o
drivers/i2c/i2c-core-of-prober.c+415−0
@@ -0,0 +1,415 @@
1+// SPDX-License-Identifier: GPL-2.0-or-later
2+/*
3+ * Linux I2C core OF component prober code
4+ *
5+ * Copyright (C) 2024 Google LLC
6+ */
7+
8+#include <linux/cleanup.h>
9+#include <linux/delay.h>
10+#include <linux/device.h>
11+#include <linux/dev_printk.h>
12+#include <linux/err.h>
13+#include <linux/gpio/consumer.h>
14+#include <linux/i2c.h>
15+#include <linux/i2c-of-prober.h>
16+#include <linux/module.h>
17+#include <linux/of.h>
18+#include <linux/regulator/consumer.h>
19+#include <linux/slab.h>
20+#include <linux/stddef.h>
21+
22+/*
23+ * Some devices, such as Google Hana Chromebooks, are produced by multiple
24+ * vendors each using their preferred components. Such components are all
25+ * in the device tree. Instead of having all of them enabled and having each
26+ * driver separately try and probe its device while fighting over shared
27+ * resources, they can be marked as "fail-needs-probe" and have a prober
28+ * figure out which one is actually used beforehand.
29+ *
30+ * This prober assumes such drop-in parts are on the same I2C bus, have
31+ * non-conflicting addresses, and can be directly probed by seeing which
32+ * address responds.
33+ *
34+ * TODO:
35+ * - Support I2C muxes
36+ */
37+
38+static struct device_node *i2c_of_probe_get_i2c_node(struct device *dev, const char *type)
39+{
40+ struct device_node *node __free(device_node) = of_find_node_by_name(NULL, type);
41+ if (!node) {
42+ dev_err(dev, "Could not find %s device node\n", type);
43+ return NULL;
44+ }
45+
46+ struct device_node *i2c_node __free(device_node) = of_get_parent(node);
47+ if (!of_node_name_eq(i2c_node, "i2c")) {
48+ dev_err(dev, "%s device isn't on I2C bus\n", type);
49+ return NULL;
50+ }
51+
52+ if (!of_device_is_available(i2c_node)) {
53+ dev_err(dev, "I2C controller not available\n");
54+ return NULL;
55+ }
56+
57+ return no_free_ptr(i2c_node);
58+}
59+
60+static int i2c_of_probe_enable_node(struct device *dev, struct device_node *node)
61+{
62+ int ret;
63+
64+ dev_dbg(dev, "Enabling %pOF\n", node);
65+
66+ struct of_changeset *ocs __free(kfree) = kzalloc(sizeof(*ocs), GFP_KERNEL);
67+ if (!ocs)
68+ return -ENOMEM;
69+
70+ of_changeset_init(ocs);
71+ ret = of_changeset_update_prop_string(ocs, node, "status", "okay");
72+ if (ret)
73+ return ret;
74+
75+ ret = of_changeset_apply(ocs);
76+ if (ret) {
77+ /* ocs needs to be explicitly cleaned up before being freed. */
78+ of_changeset_destroy(ocs);
79+ } else {
80+ /*
81+ * ocs is intentionally kept around as it needs to
82+ * exist as long as the change is applied.
83+ */
84+ void *ptr __always_unused = no_free_ptr(ocs);
85+ }
86+
87+ return ret;
88+}
89+
90+static const struct i2c_of_probe_ops i2c_of_probe_dummy_ops;
91+
92+/**
93+ * i2c_of_probe_component() - probe for devices of "type" on the same i2c bus
94+ * @dev: Pointer to the &struct device of the caller, only used for dev_printk() messages.
95+ * @cfg: Pointer to the &struct i2c_of_probe_cfg containing callbacks and other options
96+ * for the prober.
97+ * @ctx: Context data for callbacks.
98+ *
99+ * Probe for possible I2C components of the same "type" (&i2c_of_probe_cfg->type)
100+ * on the same I2C bus that have their status marked as "fail-needs-probe".
101+ *
102+ * Assumes that across the entire device tree the only instances of nodes
103+ * with "type" prefixed node names (not including the address portion) are
104+ * the ones that need handling for second source components. In other words,
105+ * if "type" is "touchscreen", then all device nodes named "touchscreen*"
106+ * are the ones that need probing. There cannot be another "touchscreen*"
107+ * node that is already enabled.
108+ *
109+ * Assumes that for each "type" of component, only one actually exists. In
110+ * other words, only one matching and existing device will be enabled.
111+ *
112+ * Context: Process context only. Does non-atomic I2C transfers.
113+ * Should only be used from a driver probe function, as the function
114+ * can return -EPROBE_DEFER if the I2C adapter or other resources
115+ * are unavailable.
116+ * Return: 0 on success or no-op, error code otherwise.
117+ * A no-op can happen when it seems like the device tree already
118+ * has components of the type to be probed already enabled. This
119+ * can happen when the device tree had not been updated to mark
120+ * the status of the to-be-probed components as "fail-needs-probe".
121+ * Or this function was already run with the same parameters and
122+ * succeeded in enabling a component. The latter could happen if
123+ * the user had multiple types of components to probe, and one of
124+ * them down the list caused a deferred probe. This is expected
125+ * behavior.
126+ */
127+int i2c_of_probe_component(struct device *dev, const struct i2c_of_probe_cfg *cfg, void *ctx)
128+{
129+ const struct i2c_of_probe_ops *ops;
130+ const char *type;
131+ struct i2c_adapter *i2c;
132+ int ret;
133+
134+ ops = cfg->ops ?: &i2c_of_probe_dummy_ops;
135+ type = cfg->type;
136+
137+ struct device_node *i2c_node __free(device_node) = i2c_of_probe_get_i2c_node(dev, type);
138+ if (!i2c_node)
139+ return -ENODEV;
140+
141+ /*
142+ * If any devices of the given "type" are already enabled then this function is a no-op.
143+ * Either the device tree hasn't been modified to work with this probe function, or the
144+ * function had already run before and enabled some component.
145+ */
146+ for_each_child_of_node_with_prefix(i2c_node, node, type)
147+ if (of_device_is_available(node))
148+ return 0;
149+
150+ i2c = of_get_i2c_adapter_by_node(i2c_node);
151+ if (!i2c)
152+ return dev_err_probe(dev, -EPROBE_DEFER, "Couldn't get I2C adapter\n");
153+
154+ /* Grab and enable resources */
155+ ret = 0;
156+ if (ops->enable)
157+ ret = ops->enable(dev, i2c_node, ctx);
158+ if (ret)
159+ goto out_put_i2c_adapter;
160+
161+ for_each_child_of_node_with_prefix(i2c_node, node, type) {
162+ union i2c_smbus_data data;
163+ u32 addr;
164+
165+ if (of_property_read_u32(node, "reg", &addr))
166+ continue;
167+ if (i2c_smbus_xfer(i2c, addr, 0, I2C_SMBUS_READ, 0, I2C_SMBUS_BYTE, &data) < 0)
168+ continue;
169+
170+ /* Found a device that is responding */
171+ if (ops->cleanup_early)
172+ ops->cleanup_early(dev, ctx);
173+ ret = i2c_of_probe_enable_node(dev, node);
174+ break;
175+ }
176+
177+ if (ops->cleanup)
178+ ops->cleanup(dev, ctx);
179+out_put_i2c_adapter:
180+ i2c_put_adapter(i2c);
181+
182+ return ret;
183+}
184+EXPORT_SYMBOL_NS_GPL(i2c_of_probe_component, I2C_OF_PROBER);
185+
186+static int i2c_of_probe_simple_get_supply(struct device *dev, struct device_node *node,
187+ struct i2c_of_probe_simple_ctx *ctx)
188+{
189+ const char *supply_name;
190+ struct regulator *supply;
191+
192+ /*
193+ * It's entirely possible for the component's device node to not have the
194+ * regulator supplies. While it does not make sense from a hardware perspective,
195+ * the supplies could be always on or otherwise not modeled in the device tree,
196+ * but the device would still work.
197+ */
198+ supply_name = ctx->opts->supply_name;
199+ if (!supply_name)
200+ return 0;
201+
202+ supply = of_regulator_get_optional(dev, node, supply_name);
203+ if (IS_ERR(supply)) {
204+ return dev_err_probe(dev, PTR_ERR(supply),
205+ "Failed to get regulator supply \"%s\" from %pOF\n",
206+ supply_name, node);
207+ }
208+
209+ ctx->supply = supply;
210+
211+ return 0;
212+}
213+
214+static void i2c_of_probe_simple_put_supply(struct i2c_of_probe_simple_ctx *ctx)
215+{
216+ regulator_put(ctx->supply);
217+ ctx->supply = NULL;
218+}
219+
220+static int i2c_of_probe_simple_enable_regulator(struct device *dev, struct i2c_of_probe_simple_ctx *ctx)
221+{
222+ int ret;
223+
224+ if (!ctx->supply)
225+ return 0;
226+
227+ dev_dbg(dev, "Enabling regulator supply \"%s\"\n", ctx->opts->supply_name);
228+
229+ ret = regulator_enable(ctx->supply);
230+ if (ret)
231+ return ret;
232+
233+ if (ctx->opts->post_power_on_delay_ms)
234+ msleep(ctx->opts->post_power_on_delay_ms);
235+
236+ return 0;
237+}
238+
239+static void i2c_of_probe_simple_disable_regulator(struct device *dev, struct i2c_of_probe_simple_ctx *ctx)
240+{
241+ if (!ctx->supply)
242+ return;
243+
244+ dev_dbg(dev, "Disabling regulator supply \"%s\"\n", ctx->opts->supply_name);
245+
246+ regulator_disable(ctx->supply);
247+}
248+
249+static int i2c_of_probe_simple_get_gpiod(struct device *dev, struct device_node *node,
250+ struct i2c_of_probe_simple_ctx *ctx)
251+{
252+ struct fwnode_handle *fwnode = of_fwnode_handle(node);
253+ struct gpio_desc *gpiod;
254+ const char *con_id;
255+
256+ /* NULL signals no GPIO needed */
257+ if (!ctx->opts->gpio_name)
258+ return 0;
259+
260+ /* An empty string signals an unnamed GPIO */
261+ if (!ctx->opts->gpio_name[0])
262+ con_id = NULL;
263+ else
264+ con_id = ctx->opts->gpio_name;
265+
266+ gpiod = fwnode_gpiod_get_index(fwnode, con_id, 0, GPIOD_ASIS, "i2c-of-prober");
267+ if (IS_ERR(gpiod))
268+ return PTR_ERR(gpiod);
269+
270+ ctx->gpiod = gpiod;
271+
272+ return 0;
273+}
274+
275+static void i2c_of_probe_simple_put_gpiod(struct i2c_of_probe_simple_ctx *ctx)
276+{
277+ gpiod_put(ctx->gpiod);
278+ ctx->gpiod = NULL;
279+}
280+
281+static int i2c_of_probe_simple_set_gpio(struct device *dev, struct i2c_of_probe_simple_ctx *ctx)
282+{
283+ int ret;
284+
285+ if (!ctx->gpiod)
286+ return 0;
287+
288+ dev_dbg(dev, "Configuring GPIO\n");
289+
290+ ret = gpiod_direction_output(ctx->gpiod, ctx->opts->gpio_assert_to_enable);
291+ if (ret)
292+ return ret;
293+
294+ if (ctx->opts->post_gpio_config_delay_ms)
295+ msleep(ctx->opts->post_gpio_config_delay_ms);
296+
297+ return 0;
298+}
299+
300+static void i2c_of_probe_simple_disable_gpio(struct device *dev, struct i2c_of_probe_simple_ctx *ctx)
301+{
302+ gpiod_set_value(ctx->gpiod, !ctx->opts->gpio_assert_to_enable);
303+}
304+
305+/**
306+ * i2c_of_probe_simple_enable - Simple helper for I2C OF prober to get and enable resources
307+ * @dev: Pointer to the &struct device of the caller, only used for dev_printk() messages
308+ * @bus_node: Pointer to the &struct device_node of the I2C adapter.
309+ * @data: Pointer to &struct i2c_of_probe_simple_ctx helper context.
310+ *
311+ * If &i2c_of_probe_simple_opts->supply_name is given, request the named regulator supply.
312+ * If &i2c_of_probe_simple_opts->gpio_name is given, request the named GPIO. Or if it is
313+ * the empty string, request the unnamed GPIO.
314+ * If a regulator supply was found, enable that regulator.
315+ * If a GPIO line was found, configure the GPIO line to output and set value
316+ * according to given options.
317+ *
318+ * Return: %0 on success or no-op, or a negative error number on failure.
319+ */
320+int i2c_of_probe_simple_enable(struct device *dev, struct device_node *bus_node, void *data)
321+{
322+ struct i2c_of_probe_simple_ctx *ctx = data;
323+ struct device_node *node;
324+ const char *compat;
325+ int ret;
326+
327+ dev_dbg(dev, "Requesting resources for components under I2C bus %pOF\n", bus_node);
328+
329+ if (!ctx || !ctx->opts)
330+ return -EINVAL;
331+
332+ compat = ctx->opts->res_node_compatible;
333+ if (!compat)
334+ return -EINVAL;
335+
336+ node = of_get_compatible_child(bus_node, compat);
337+ if (!node)
338+ return dev_err_probe(dev, -ENODEV, "No device compatible with \"%s\" found\n",
339+ compat);
340+
341+ ret = i2c_of_probe_simple_get_supply(dev, node, ctx);
342+ if (ret)
343+ goto out_put_node;
344+
345+ ret = i2c_of_probe_simple_get_gpiod(dev, node, ctx);
346+ if (ret)
347+ goto out_put_supply;
348+
349+ ret = i2c_of_probe_simple_enable_regulator(dev, ctx);
350+ if (ret)
351+ goto out_put_gpiod;
352+
353+ ret = i2c_of_probe_simple_set_gpio(dev, ctx);
354+ if (ret)
355+ goto out_disable_regulator;
356+
357+ return 0;
358+
359+out_disable_regulator:
360+ i2c_of_probe_simple_disable_regulator(dev, ctx);
361+out_put_gpiod:
362+ i2c_of_probe_simple_put_gpiod(ctx);
363+out_put_supply:
364+ i2c_of_probe_simple_put_supply(ctx);
365+out_put_node:
366+ of_node_put(node);
367+ return ret;
368+}
369+EXPORT_SYMBOL_NS_GPL(i2c_of_probe_simple_enable, I2C_OF_PROBER);
370+
371+/**
372+ * i2c_of_probe_simple_cleanup_early - \
373+ * Simple helper for I2C OF prober to release GPIOs before component is enabled
374+ * @dev: Pointer to the &struct device of the caller; unused.
375+ * @data: Pointer to &struct i2c_of_probe_simple_ctx helper context.
376+ *
377+ * GPIO descriptors are exclusive and have to be released before the
378+ * actual driver probes so that the latter can acquire them.
379+ */
380+void i2c_of_probe_simple_cleanup_early(struct device *dev, void *data)
381+{
382+ struct i2c_of_probe_simple_ctx *ctx = data;
383+
384+ i2c_of_probe_simple_put_gpiod(ctx);
385+}
386+EXPORT_SYMBOL_NS_GPL(i2c_of_probe_simple_cleanup_early, I2C_OF_PROBER);
387+
388+/**
389+ * i2c_of_probe_simple_cleanup - Clean up and release resources for I2C OF prober simple helpers
390+ * @dev: Pointer to the &struct device of the caller, only used for dev_printk() messages
391+ * @data: Pointer to &struct i2c_of_probe_simple_ctx helper context.
392+ *
393+ * * If a GPIO line was found and not yet released, set its value to the opposite of that
394+ * set in i2c_of_probe_simple_enable() and release it.
395+ * * If a regulator supply was found, disable that regulator and release it.
396+ */
397+void i2c_of_probe_simple_cleanup(struct device *dev, void *data)
398+{
399+ struct i2c_of_probe_simple_ctx *ctx = data;
400+
401+ /* GPIO operations here are no-ops if i2c_of_probe_simple_cleanup_early was called. */
402+ i2c_of_probe_simple_disable_gpio(dev, ctx);
403+ i2c_of_probe_simple_put_gpiod(ctx);
404+
405+ i2c_of_probe_simple_disable_regulator(dev, ctx);
406+ i2c_of_probe_simple_put_supply(ctx);
407+}
408+EXPORT_SYMBOL_NS_GPL(i2c_of_probe_simple_cleanup, I2C_OF_PROBER);
409+
410+struct i2c_of_probe_ops i2c_of_probe_simple_ops = {
411+ .enable = i2c_of_probe_simple_enable,
412+ .cleanup_early = i2c_of_probe_simple_cleanup_early,
413+ .cleanup = i2c_of_probe_simple_cleanup,
414+};
415+EXPORT_SYMBOL_NS_GPL(i2c_of_probe_simple_ops, I2C_OF_PROBER);
drivers/i2c/i2c-core-smbus.c+1−1
@@ -122,7 +122,7 @@ EXPORT_SYMBOL(i2c_smbus_read_byte); · 121 unmodified lines
122122 s32 i2c_smbus_write_byte(const struct i2c_client *client, u8 value)
123123 {
124124 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
125− I2C_SMBUS_WRITE, value, I2C_SMBUS_BYTE, NULL);
125+ I2C_SMBUS_WRITE, value, I2C_SMBUS_BYTE, NULL);
126126 }
127127 EXPORT_SYMBOL(i2c_smbus_write_byte);
128128
drivers/of/base.c+36−0
@@ -644,6 +644,42 @@ struct device_node *of_get_next_child(const struct device_node *node, · 643 unmodified lines
644644 }
645645 EXPORT_SYMBOL(of_get_next_child);
646646
647+/**
648+ * of_get_next_child_with_prefix - Find the next child node with prefix
649+ * @node: parent node
650+ * @prev: previous child of the parent node, or NULL to get first
651+ * @prefix: prefix that the node name should have
652+ *
653+ * This function is like of_get_next_child(), except that it automatically
654+ * skips any nodes whose name doesn't have the given prefix.
655+ *
656+ * Return: A node pointer with refcount incremented, use
657+ * of_node_put() on it when done.
658+ */
659+struct device_node *of_get_next_child_with_prefix(const struct device_node *node,
660+ struct device_node *prev,
661+ const char *prefix)
662+{
663+ struct device_node *next;
664+ unsigned long flags;
665+
666+ if (!node)
667+ return NULL;
668+
669+ raw_spin_lock_irqsave(&devtree_lock, flags);
670+ next = prev ? prev->sibling : node->child;
671+ for (; next; next = next->sibling) {
672+ if (!of_node_name_prefix(next, prefix))
673+ continue;
674+ if (of_node_get(next))
675+ break;
676+ }
677+ of_node_put(prev);
678+ raw_spin_unlock_irqrestore(&devtree_lock, flags);
679+ return next;
680+}
681+EXPORT_SYMBOL(of_get_next_child_with_prefix);
682+
647683 static struct device_node *of_get_next_status_child(const struct device_node *node,
648684 struct device_node *prev,
649685 bool (*checker)(const struct device_node *))
drivers/of/dynamic.c+44−0
@@ -1072,3 +1072,47 @@ int of_changeset_add_prop_bool(struct of_changeset *ocs, struct device_node *np, · 1071 unmodified lines
10721072 return of_changeset_add_prop_helper(ocs, np, &prop);
10731073 }
10741074 EXPORT_SYMBOL_GPL(of_changeset_add_prop_bool);
1075+
1076+static int of_changeset_update_prop_helper(struct of_changeset *ocs,
1077+ struct device_node *np,
1078+ const struct property *pp)
1079+{
1080+ struct property *new_pp;
1081+ int ret;
1082+
1083+ new_pp = __of_prop_dup(pp, GFP_KERNEL);
1084+ if (!new_pp)
1085+ return -ENOMEM;
1086+
1087+ ret = of_changeset_update_property(ocs, np, new_pp);
1088+ if (ret)
1089+ __of_prop_free(new_pp);
1090+
1091+ return ret;
1092+}
1093+
1094+/**
1095+ * of_changeset_update_prop_string - Add a string property update to a changeset
1096+ *
1097+ * @ocs: changeset pointer
1098+ * @np: device node pointer
1099+ * @prop_name: name of the property to be updated
1100+ * @str: pointer to null terminated string
1101+ *
1102+ * Create a string property to be updated and add it to a changeset.
1103+ *
1104+ * Return: 0 on success, a negative error value in case of an error.
1105+ */
1106+int of_changeset_update_prop_string(struct of_changeset *ocs,
1107+ struct device_node *np,
1108+ const char *prop_name, const char *str)
1109+{
1110+ struct property prop = {
1111+ .name = (char *)prop_name,
1112+ .length = strlen(str) + 1,
1113+ .value = (void *)str,
1114+ };
1115+
1116+ return of_changeset_update_prop_helper(ocs, np, &prop);
1117+}
1118+EXPORT_SYMBOL_GPL(of_changeset_update_prop_string);
drivers/platform/chrome/Kconfig+11−0
@@ -61,6 +61,17 @@ config CHROMEOS_TBMC · 60 unmodified lines
6161 To compile this driver as a module, choose M here: the
6262 module will be called chromeos_tbmc.
6363
64+config CHROMEOS_OF_HW_PROBER
65+ tristate "ChromeOS Device Tree Hardware Prober"
66+ depends on OF
67+ depends on I2C
68+ select OF_DYNAMIC
69+ default OF
70+ help
71+ This option enables the device tree hardware prober for ChromeOS
72+ devices. The driver will probe the correct component variant in
73+ devices that have multiple drop-in options for one component.
74+
6475 config CROS_EC
6576 tristate "ChromeOS Embedded Controller"
6677 select CROS_EC_PROTO
drivers/platform/chrome/Makefile+1−0
@@ -6,6 +6,7 @@ CFLAGS_cros_ec_sensorhub_ring.o:= -I$(src) · 5 unmodified lines
66
77 obj-$(CONFIG_CHROMEOS_ACPI) += chromeos_acpi.o
88 obj-$(CONFIG_CHROMEOS_LAPTOP) += chromeos_laptop.o
9+obj-$(CONFIG_CHROMEOS_OF_HW_PROBER) += chromeos_of_hw_prober.o
910 obj-$(CONFIG_CHROMEOS_PRIVACY_SCREEN) += chromeos_privacy_screen.o
1011 obj-$(CONFIG_CHROMEOS_PSTORE) += chromeos_pstore.o
1112 obj-$(CONFIG_CHROMEOS_TBMC) += chromeos_tbmc.o
drivers/platform/chrome/chromeos_of_hw_prober.c+154−0
@@ -0,0 +1,154 @@
1+// SPDX-License-Identifier: GPL-2.0-only
2+/*
3+ * ChromeOS Device Tree Hardware Prober
4+ *
5+ * Copyright (c) 2024 Google LLC
6+ */
7+
8+#include <linux/array_size.h>
9+#include <linux/errno.h>
10+#include <linux/i2c-of-prober.h>
11+#include <linux/module.h>
12+#include <linux/of.h>
13+#include <linux/platform_device.h>
14+#include <linux/stddef.h>
15+
16+#define DRV_NAME "chromeos_of_hw_prober"
17+
18+/**
19+ * struct hw_prober_entry - Holds an entry for the hardware prober
20+ *
21+ * @compatible: compatible string to match against the machine
22+ * @prober: prober function to call when machine matches
23+ * @data: extra data for the prober function
24+ */
25+struct hw_prober_entry {
26+ const char *compatible;
27+ int (*prober)(struct device *dev, const void *data);
28+ const void *data;
29+};
30+
31+struct chromeos_i2c_probe_data {
32+ const struct i2c_of_probe_cfg *cfg;
33+ const struct i2c_of_probe_simple_opts *opts;
34+};
35+
36+static int chromeos_i2c_component_prober(struct device *dev, const void *_data)
37+{
38+ const struct chromeos_i2c_probe_data *data = _data;
39+ struct i2c_of_probe_simple_ctx ctx = {
40+ .opts = data->opts,
41+ };
42+
43+ return i2c_of_probe_component(dev, data->cfg, &ctx);
44+}
45+
46+#define DEFINE_CHROMEOS_I2C_PROBE_CFG_SIMPLE_BY_TYPE(_type) \
47+ static const struct i2c_of_probe_cfg chromeos_i2c_probe_simple_ ## _type ## _cfg = { \
48+ .type = #_type, \
49+ .ops = &i2c_of_probe_simple_ops, \
50+ }
51+
52+#define DEFINE_CHROMEOS_I2C_PROBE_DATA_DUMB_BY_TYPE(_type) \
53+ static const struct chromeos_i2c_probe_data chromeos_i2c_probe_dumb_ ## _type = { \
54+ .cfg = &(const struct i2c_of_probe_cfg) { \
55+ .type = #_type, \
56+ }, \
57+ }
58+
59+DEFINE_CHROMEOS_I2C_PROBE_DATA_DUMB_BY_TYPE(touchscreen);
60+
61+DEFINE_CHROMEOS_I2C_PROBE_CFG_SIMPLE_BY_TYPE(trackpad);
62+
63+static const struct chromeos_i2c_probe_data chromeos_i2c_probe_hana_trackpad = {
64+ .cfg = &chromeos_i2c_probe_simple_trackpad_cfg,
65+ .opts = &(const struct i2c_of_probe_simple_opts) {
66+ .res_node_compatible = "elan,ekth3000",
67+ .supply_name = "vcc",
68+ /*
69+ * ELAN trackpad needs 2 ms for H/W init and 100 ms for F/W init.
70+ * Synaptics trackpad needs 100 ms.
71+ * However, the regulator is set to "always-on", presumably to
72+ * avoid this delay. The ELAN driver is also missing delays.
73+ */
74+ .post_power_on_delay_ms = 0,
75+ },
76+};
77+
78+static const struct hw_prober_entry hw_prober_platforms[] = {
79+ {
80+ .compatible = "google,hana",
81+ .prober = chromeos_i2c_component_prober,
82+ .data = &chromeos_i2c_probe_dumb_touchscreen,
83+ }, {
84+ .compatible = "google,hana",
85+ .prober = chromeos_i2c_component_prober,
86+ .data = &chromeos_i2c_probe_hana_trackpad,
87+ },
88+};
89+
90+static int chromeos_of_hw_prober_probe(struct platform_device *pdev)
91+{
92+ for (size_t i = 0; i < ARRAY_SIZE(hw_prober_platforms); i++) {
93+ int ret;
94+
95+ if (!of_machine_is_compatible(hw_prober_platforms[i].compatible))
96+ continue;
97+
98+ ret = hw_prober_platforms[i].prober(&pdev->dev, hw_prober_platforms[i].data);
99+ /* Ignore unrecoverable errors and keep going through other probers */
100+ if (ret == -EPROBE_DEFER)
101+ return ret;
102+ }
103+
104+ return 0;
105+}
106+
107+static struct platform_driver chromeos_of_hw_prober_driver = {
108+ .probe = chromeos_of_hw_prober_probe,
109+ .driver = {
110+ .name = DRV_NAME,
111+ },
112+};
113+
114+static struct platform_device *chromeos_of_hw_prober_pdev;
115+
116+static int chromeos_of_hw_prober_driver_init(void)
117+{
118+ size_t i;
119+ int ret;
120+
121+ for (i = 0; i < ARRAY_SIZE(hw_prober_platforms); i++)
122+ if (of_machine_is_compatible(hw_prober_platforms[i].compatible))
123+ break;
124+ if (i == ARRAY_SIZE(hw_prober_platforms))
125+ return -ENODEV;
126+
127+ ret = platform_driver_register(&chromeos_of_hw_prober_driver);
128+ if (ret)
129+ return ret;
130+
131+ chromeos_of_hw_prober_pdev =
132+ platform_device_register_simple(DRV_NAME, PLATFORM_DEVID_NONE, NULL, 0);
133+ if (IS_ERR(chromeos_of_hw_prober_pdev))
134+ goto err;
135+
136+ return 0;
137+
138+err:
139+ platform_driver_unregister(&chromeos_of_hw_prober_driver);
140+
141+ return PTR_ERR(chromeos_of_hw_prober_pdev);
142+}
143+module_init(chromeos_of_hw_prober_driver_init);
144+
145+static void chromeos_of_hw_prober_driver_exit(void)
146+{
147+ platform_device_unregister(chromeos_of_hw_prober_pdev);
148+ platform_driver_unregister(&chromeos_of_hw_prober_driver);
149+}
150+module_exit(chromeos_of_hw_prober_driver_exit);
151+
152+MODULE_LICENSE("GPL");
153+MODULE_DESCRIPTION("ChromeOS device tree hardware prober");
154+MODULE_IMPORT_NS(I2C_OF_PROBER);
include/linux/i2c-of-prober.h+140−0
@@ -0,0 +1,140 @@
1+/* SPDX-License-Identifier: GPL-2.0-or-later */
2+/*
3+ * Definitions for the Linux I2C OF component prober
4+ *
5+ * Copyright (C) 2024 Google LLC
6+ */
7+
8+#ifndef _LINUX_I2C_OF_PROBER_H
9+#define _LINUX_I2C_OF_PROBER_H
10+
11+#include <linux/kconfig.h>
12+#include <linux/types.h>
13+
14+struct device;
15+struct device_node;
16+
17+/**
18+ * struct i2c_of_probe_ops - I2C OF component prober callbacks
19+ *
20+ * A set of callbacks to be used by i2c_of_probe_component().
21+ *
22+ * All callbacks are optional. Callbacks are called only once per run, and are
23+ * used in the order they are defined in this structure.
24+ *
25+ * All callbacks that have return values shall return %0 on success,
26+ * or a negative error number on failure.
27+ *
28+ * The @dev parameter passed to the callbacks is the same as @dev passed to
29+ * i2c_of_probe_component(). It should only be used for dev_printk() calls
30+ * and nothing else, especially not managed device resource (devres) APIs.
31+ */
32+struct i2c_of_probe_ops {
33+ /**
34+ * @enable: Retrieve and enable resources so that the components respond to probes.
35+ *
36+ * It is OK for this callback to return -EPROBE_DEFER since the intended use includes
37+ * retrieving resources and enables them. Resources should be reverted to their initial
38+ * state and released before returning if this fails.
39+ */
40+ int (*enable)(struct device *dev, struct device_node *bus_node, void *data);
41+
42+ /**
43+ * @cleanup_early: Release exclusive resources prior to calling probe() on a
44+ * detected component.
45+ *
46+ * Only called if a matching component is actually found. If none are found,
47+ * resources that would have been released in this callback should be released in
48+ * @free_resourcs_late instead.
49+ */
50+ void (*cleanup_early)(struct device *dev, void *data);
51+
52+ /**
53+ * @cleanup: Opposite of @enable to balance refcounts and free resources after probing.
54+ *
55+ * Should check if resources were already freed by @cleanup_early.
56+ */
57+ void (*cleanup)(struct device *dev, void *data);
58+};
59+
60+/**
61+ * struct i2c_of_probe_cfg - I2C OF component prober configuration
62+ * @ops: Callbacks for the prober to use.
63+ * @type: A string to match the device node name prefix to probe for.
64+ */
65+struct i2c_of_probe_cfg {
66+ const struct i2c_of_probe_ops *ops;
67+ const char *type;
68+};
69+
70+#if IS_ENABLED(CONFIG_OF_DYNAMIC)
71+
72+int i2c_of_probe_component(struct device *dev, const struct i2c_of_probe_cfg *cfg, void *ctx);
73+
74+/**
75+ * DOC: I2C OF component prober simple helpers
76+ *
77+ * Components such as trackpads are commonly connected to a devices baseboard
78+ * with a 6-pin ribbon cable. That gives at most one voltage supply and one
79+ * GPIO (commonly a "enable" or "reset" line) besides the I2C bus, interrupt
80+ * pin, and common ground. Touchscreens, while integrated into the display
81+ * panel's connection, typically have the same set of connections.
82+ *
83+ * A simple set of helpers are provided here for use with the I2C OF component
84+ * prober. This implementation targets such components, allowing for at most
85+ * one regulator supply.
86+ *
87+ * The following helpers are provided:
88+ * * i2c_of_probe_simple_enable()
89+ * * i2c_of_probe_simple_cleanup_early()
90+ * * i2c_of_probe_simple_cleanup()
91+ */
92+
93+/**
94+ * struct i2c_of_probe_simple_opts - Options for simple I2C component prober callbacks
95+ * @res_node_compatible: Compatible string of device node to retrieve resources from.
96+ * @supply_name: Name of regulator supply.
97+ * @gpio_name: Name of GPIO. NULL if no GPIO line is used. Empty string ("") if GPIO
98+ * line is unnamed.
99+ * @post_power_on_delay_ms: Delay after regulators are powered on. Passed to msleep().
100+ * @post_gpio_config_delay_ms: Delay after GPIO is configured. Passed to msleep().
101+ * @gpio_assert_to_enable: %true if GPIO should be asserted, i.e. set to logical high,
102+ * to enable the component.
103+ *
104+ * This describes power sequences common for the class of components supported by the
105+ * simple component prober:
106+ * * @gpio_name is configured to the non-active setting according to @gpio_assert_to_enable.
107+ * * @supply_name regulator supply is enabled.
108+ * * Wait for @post_power_on_delay_ms to pass.
109+ * * @gpio_name is configured to the active setting according to @gpio_assert_to_enable.
110+ * * Wait for @post_gpio_config_delay_ms to pass.
111+ */
112+struct i2c_of_probe_simple_opts {
113+ const char *res_node_compatible;
114+ const char *supply_name;
115+ const char *gpio_name;
116+ unsigned int post_power_on_delay_ms;
117+ unsigned int post_gpio_config_delay_ms;
118+ bool gpio_assert_to_enable;
119+};
120+
121+struct gpio_desc;
122+struct regulator;
123+
124+struct i2c_of_probe_simple_ctx {
125+ /* public: provided by user before helpers are used. */
126+ const struct i2c_of_probe_simple_opts *opts;
127+ /* private: internal fields for helpers. */
128+ struct regulator *supply;
129+ struct gpio_desc *gpiod;
130+};
131+
132+int i2c_of_probe_simple_enable(struct device *dev, struct device_node *bus_node, void *data);
133+void i2c_of_probe_simple_cleanup_early(struct device *dev, void *data);
134+void i2c_of_probe_simple_cleanup(struct device *dev, void *data);
135+
136+extern struct i2c_of_probe_ops i2c_of_probe_simple_ops;
137+
138+#endif /* IS_ENABLED(CONFIG_OF_DYNAMIC) */
139+
140+#endif /* _LINUX_I2C_OF_PROBER_H */
include/linux/of.h+13−0
@@ -289,6 +289,9 @@ extern struct device_node *of_get_parent(const struct device_node *node); · 288 unmodified lines
289289 extern struct device_node *of_get_next_parent(struct device_node *node);
290290 extern struct device_node *of_get_next_child(const struct device_node *node,
291291 struct device_node *prev);
292+extern struct device_node *of_get_next_child_with_prefix(const struct device_node *node,
293+ struct device_node *prev,
294+ const char *prefix);
292295 extern struct device_node *of_get_next_available_child(
293296 const struct device_node *node, struct device_node *prev);
294297 extern struct device_node *of_get_next_reserved_child(
@@ -1468,6 +1471,12 @@ static inline int of_property_read_s32(const struct device_node *np, · 1173 unmodified lines
14681471 child != NULL; \
14691472 child = of_get_next_child(parent, child))
14701473
1474+#define for_each_child_of_node_with_prefix(parent, child, prefix) \
1475+ for (struct device_node *child __free(device_node) = \
1476+ of_get_next_child_with_prefix(parent, NULL, prefix); \
1477+ child != NULL; \
1478+ child = of_get_next_child_with_prefix(parent, child, prefix))
1479+
14711480 #define for_each_available_child_of_node(parent, child) \
14721481 for (child = of_get_next_available_child(parent, NULL); child != NULL; \
14731482 child = of_get_next_available_child(parent, child))
@@ -1651,6 +1660,10 @@ static inline int of_changeset_add_prop_u32(struct of_changeset *ocs, · 177 unmodified lines
16511660 return of_changeset_add_prop_u32_array(ocs, np, prop_name, &val, 1);
16521661 }
16531662
1663+int of_changeset_update_prop_string(struct of_changeset *ocs,
1664+ struct device_node *np,
1665+ const char *prop_name, const char *str);
1666+
16541667 int of_changeset_add_prop_bool(struct of_changeset *ocs, struct device_node *np,
16551668 const char *prop_name);
16561669

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