// SPDX-License-Identifier: GPL-2.0-only OR MIT/* * Apple SMC RTC driver * Copyright The Asahi Linux Contributors */ #include <linux/bitops.h>#include <linux/mfd/macsmc.h>#include <linux/module.h>#include <linux/nvmem-consumer.h>#include <linux/of.h>#include <linux/platform_device.h>#include <linux/rtc.h>#include <linux/slab.h> /* 48-bit RTC */#define RTC_BYTES 6#define RTC_BITS (8 * RTC_BYTES) /* 32768 Hz clock */#define RTC_SEC_SHIFT 15 struct macsmc_rtc {	struct device *dev;	struct apple_smc *smc;	struct rtc_device *rtc_dev;	struct nvmem_cell *rtc_offset;}; static int macsmc_rtc_get_time(struct device *dev, struct rtc_time *tm){	struct macsmc_rtc *rtc = dev_get_drvdata(dev);	u64 ctr = 0, off = 0;	time64_t now;	void *p_off;	size_t len;	int ret; 	ret = apple_smc_read(rtc->smc, SMC_KEY(CLKM), &ctr, RTC_BYTES);	if (ret < 0)		return ret;	if (ret != RTC_BYTES)		return -EIO; 	p_off = nvmem_cell_read(rtc->rtc_offset, &len);	if (IS_ERR(p_off))		return PTR_ERR(p_off);	if (len < RTC_BYTES) {		kfree(p_off);		return -EIO;	} 	memcpy(&off, p_off, RTC_BYTES);	kfree(p_off); 	/* Sign extend from 48 to 64 bits, then arithmetic shift right 15 bits to get seconds */	now = sign_extend64(ctr + off, RTC_BITS - 1) >> RTC_SEC_SHIFT;	rtc_time64_to_tm(now, tm); 	return ret;} static int macsmc_rtc_set_time(struct device *dev, struct rtc_time *tm){	struct macsmc_rtc *rtc = dev_get_drvdata(dev);	u64 ctr = 0, off = 0;	int ret; 	ret = apple_smc_read(rtc->smc, SMC_KEY(CLKM), &ctr, RTC_BYTES);	if (ret < 0)		return ret;	if (ret != RTC_BYTES)		return -EIO; 	/* This sets the offset such that the set second begins now */	off = (rtc_tm_to_time64(tm) << RTC_SEC_SHIFT) - ctr;	return nvmem_cell_write(rtc->rtc_offset, &off, RTC_BYTES);} static const struct rtc_class_ops macsmc_rtc_ops = {	.read_time = macsmc_rtc_get_time,	.set_time = macsmc_rtc_set_time,}; static int macsmc_rtc_probe(struct platform_device *pdev){	struct apple_smc *smc = dev_get_drvdata(pdev->dev.parent);	struct macsmc_rtc *rtc; 	/*	 * MFD will probe this device even without a node in the device tree,	 * thus bail out early if the SMC on the current machines does not	 * support RTC and has no node in the device tree.	 */	if (!pdev->dev.of_node)		return -ENODEV; 	rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);	if (!rtc)		return -ENOMEM; 	rtc->dev = &pdev->dev;	rtc->smc = smc; 	rtc->rtc_offset = devm_nvmem_cell_get(&pdev->dev, "rtc_offset");	if (IS_ERR(rtc->rtc_offset))		return dev_err_probe(&pdev->dev, PTR_ERR(rtc->rtc_offset),				     "Failed to get rtc_offset NVMEM cell\n"); 	rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);	if (IS_ERR(rtc->rtc_dev))		return PTR_ERR(rtc->rtc_dev); 	rtc->rtc_dev->ops = &macsmc_rtc_ops;	rtc->rtc_dev->range_min = S64_MIN >> (RTC_SEC_SHIFT + (64 - RTC_BITS));	rtc->rtc_dev->range_max = S64_MAX >> (RTC_SEC_SHIFT + (64 - RTC_BITS)); 	platform_set_drvdata(pdev, rtc); 	return devm_rtc_register_device(rtc->rtc_dev);} static const struct of_device_id macsmc_rtc_of_table[] = {	{ .compatible = "apple,smc-rtc", },	{}};MODULE_DEVICE_TABLE(of, macsmc_rtc_of_table); static struct platform_driver macsmc_rtc_driver = {	.driver = {		.name = "macsmc-rtc",		.of_match_table = macsmc_rtc_of_table,	},	.probe = macsmc_rtc_probe,};module_platform_driver(macsmc_rtc_driver); MODULE_LICENSE("Dual MIT/GPL");MODULE_DESCRIPTION("Apple SMC RTC driver");MODULE_AUTHOR("Hector Martin <marcan@marcan.st>");