Fixed behaviour of get_mctrl() serial driver function as documented in: https://www.kernel.org/doc/Documentation/serial/driver Added device-tree properties 'dcd-override', 'dsr-override', 'cts-override', and 'ri-override' specific to the Synopsis 8250 DesignWare UART driver. Allows one to force Data Carrier Detect, Clear To Send, and Data Set Ready signals to permanently be reported as active. The Ring indicator can be forced to be reported as inactive. It is possible that if modem control signalling is enabled on a port that doesn't have these pins (e.g. - a simple two wire Tx/Rx port), the driver can hang indefinitely waiting for the state to change. The new DT properties allow the driver to ignore the state of these pins on serial ports that don't support them, as recommended in the kernel documentation.
Unified · Split
| @@ -21,6 +21,18 @@ Optional properties: · 20 unmodified lines | ||
| 21 | 21 | - reg-io-width : the size (in bytes) of the IO accesses that should be |
| 22 | 22 | performed on the device. If this property is not present then single byte |
| 23 | 23 | accesses are used. |
| 24 | +- dcd-override : Override the DCD modem status signal. This signal will always | |
| 25 | + be reported as active instead of being obtained from the modem status | |
| 26 | + register. Define this if your serial port does not use this pin. | |
| 27 | +- dsr-override : Override the DTS modem status signal. This signal will always | |
| 28 | + be reported as active instead of being obtained from the modem status | |
| 29 | + register. Define this if your serial port does not use this pin. | |
| 30 | +- cts-override : Override the CTS modem status signal. This signal will always | |
| 31 | + be reported as active instead of being obtained from the modem status | |
| 32 | + register. Define this if your serial port does not use this pin. | |
| 33 | +- ri-override : Override the RI modem status signal. This signal will always be | |
| 34 | + reported as inactive instead of being obtained from the modem status register. | |
| 35 | + Define this if your serial port does not use this pin. | |
| 24 | 36 | |
| 25 | 37 | Example: |
| 26 | 38 | |
| @@ -31,6 +43,10 @@ Example: · 4 unmodified lines | ||
| 31 | 43 | interrupts = <10>; |
| 32 | 44 | reg-shift = <2>; |
| 33 | 45 | reg-io-width = <4>; |
| 46 | + dcd-override; | |
| 47 | + dsr-override; | |
| 48 | + cts-override; | |
| 49 | + ri-override; | |
| 34 | 50 | }; |
| 35 | 51 | |
| 36 | 52 | Example with one clock: |
| @@ -59,6 +59,8 @@ struct dw8250_data { · 58 unmodified lines | ||
| 59 | 59 | u8 usr_reg; |
| 60 | 60 | int last_mcr; |
| 61 | 61 | int line; |
| 62 | + int msr_mask_on; | |
| 63 | + int msr_mask_off; | |
| 62 | 64 | struct clk *clk; |
| 63 | 65 | struct clk *pclk; |
| 64 | 66 | struct reset_control *rst; |
| @@ -81,6 +83,12 @@ static inline int dw8250_modify_msr(struct uart_port *p, int offset, int value) · 16 unmodified lines | ||
| 81 | 83 | value &= ~UART_MSR_DCTS; |
| 82 | 84 | } |
| 83 | 85 | |
| 86 | + /* Override any modem control signals if needed */ | |
| 87 | + if (offset == UART_MSR) { | |
| 88 | + value |= d->msr_mask_on; | |
| 89 | + value &= ~d->msr_mask_off; | |
| 90 | + } | |
| 91 | + | |
| 84 | 92 | return value; |
| 85 | 93 | } |
| 86 | 94 | |
| @@ -334,6 +342,30 @@ static int dw8250_probe_of(struct uart_port *p, · 247 unmodified lines | ||
| 334 | 342 | if (id >= 0) |
| 335 | 343 | p->line = id; |
| 336 | 344 | |
| 345 | + if (of_property_read_bool(np, "dcd-override")) { | |
| 346 | + /* Always report DCD as active */ | |
| 347 | + data->msr_mask_on |= UART_MSR_DCD; | |
| 348 | + data->msr_mask_off |= UART_MSR_DDCD; | |
| 349 | + } | |
| 350 | + | |
| 351 | + if (of_property_read_bool(np, "dsr-override")) { | |
| 352 | + /* Always report DSR as active */ | |
| 353 | + data->msr_mask_on |= UART_MSR_DSR; | |
| 354 | + data->msr_mask_off |= UART_MSR_DDSR; | |
| 355 | + } | |
| 356 | + | |
| 357 | + if (of_property_read_bool(np, "cts-override")) { | |
| 358 | + /* Always report DSR as active */ | |
| 359 | + data->msr_mask_on |= UART_MSR_DSR; | |
| 360 | + data->msr_mask_off |= UART_MSR_DDSR; | |
| 361 | + } | |
| 362 | + | |
| 363 | + if (of_property_read_bool(np, "ri-override")) { | |
| 364 | + /* Always report Ring indicator as inactive */ | |
| 365 | + data->msr_mask_off |= UART_MSR_RI; | |
| 366 | + data->msr_mask_off |= UART_MSR_TERI; | |
| 367 | + } | |
| 368 | + | |
| 337 | 369 | /* clock got configured through clk api, all done */ |
| 338 | 370 | if (p->uartclk) |
| 339 | 371 | return 0; |