diff options
| author | Alexander Shiyan <shc_work@mail.ru> | 2018-12-20 09:19:30 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-12-20 16:26:59 +0100 |
| commit | efa0f49496be359ab3e068b0a75b15808c354b7f (patch) | |
| tree | 159884816faaa3c64a7b7e678d467c97b47f610e /drivers/tty/serial/sccnxp.c | |
| parent | 4ce193fdba48516717a4840043abb83f71109ee2 (diff) | |
serial: sccnxp: Allow to use non-standard baud rates
This patch adds support for the use of non-standard baud rates.
For these purposes, we use the built-in timer/counter.
Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serial/sccnxp.c')
| -rw-r--r-- | drivers/tty/serial/sccnxp.c | 22 |
1 files changed, 19 insertions, 3 deletions
diff --git a/drivers/tty/serial/sccnxp.c b/drivers/tty/serial/sccnxp.c index c0a68eee4479..68a24a14f6b7 100644 --- a/drivers/tty/serial/sccnxp.c +++ b/drivers/tty/serial/sccnxp.c @@ -48,7 +48,6 @@ # define MR2_STOP1 (7 << 0) # define MR2_STOP2 (0xf << 0) #define SCCNXP_SR_REG (0x01) -#define SCCNXP_CSR_REG SCCNXP_SR_REG # define SR_RXRDY (1 << 0) # define SR_FULL (1 << 1) # define SR_TXRDY (1 << 2) @@ -57,6 +56,8 @@ # define SR_PE (1 << 5) # define SR_FE (1 << 6) # define SR_BRK (1 << 7) +#define SCCNXP_CSR_REG (SCCNXP_SR_REG) +# define CSR_TIMER_MODE (0x0d) #define SCCNXP_CR_REG (0x02) # define CR_RX_ENABLE (1 << 0) # define CR_RX_DISABLE (1 << 1) @@ -83,9 +84,12 @@ # define IMR_RXRDY (1 << 1) # define ISR_TXRDY(x) (1 << ((x * 4) + 0)) # define ISR_RXRDY(x) (1 << ((x * 4) + 1)) +#define SCCNXP_CTPU_REG (0x06) +#define SCCNXP_CTPL_REG (0x07) #define SCCNXP_IPR_REG (0x0d) #define SCCNXP_OPCR_REG SCCNXP_IPR_REG #define SCCNXP_SOP_REG (0x0e) +#define SCCNXP_START_COUNTER_REG SCCNXP_SOP_REG #define SCCNXP_ROP_REG (0x0f) /* Route helpers */ @@ -255,7 +259,7 @@ static int sccnxp_update_best_err(int a, int b, int *besterr) { int err = abs(a - b); - if ((*besterr < 0) || (*besterr > err)) { + if (*besterr > err) { *besterr = err; return 0; } @@ -303,10 +307,22 @@ static const struct { static int sccnxp_set_baud(struct uart_port *port, int baud) { struct sccnxp_port *s = dev_get_drvdata(port->dev); - int div_std, tmp_baud, bestbaud = baud, besterr = -1; + int div_std, tmp_baud, bestbaud = INT_MAX, besterr = INT_MAX; struct sccnxp_chip *chip = s->chip; u8 i, acr = 0, csr = 0, mr0 = 0; + /* Find divisor to load to the timer preset registers */ + div_std = DIV_ROUND_CLOSEST(port->uartclk, 2 * 16 * baud); + if ((div_std >= 2) && (div_std <= 0xffff)) { + bestbaud = DIV_ROUND_CLOSEST(port->uartclk, 2 * 16 * div_std); + sccnxp_update_best_err(baud, bestbaud, &besterr); + csr = CSR_TIMER_MODE; + sccnxp_port_write(port, SCCNXP_CTPU_REG, div_std >> 8); + sccnxp_port_write(port, SCCNXP_CTPL_REG, div_std); + /* Issue start timer/counter command */ + sccnxp_port_read(port, SCCNXP_START_COUNTER_REG); + } + /* Find best baud from table */ for (i = 0; baud_std[i].baud && besterr; i++) { if (baud_std[i].mr0 && !(chip->flags & SCCNXP_HAVE_MR0)) |