2 files changed, 32 insertions, 7 deletions

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index d5239d5ff98b..e4bf0e435af6 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -65,6 +65,7 @@ struct sci_port {
         struct plat_sci_port    *cfg;
         int                     overrun_bit;
         unsigned int            error_mask;
+        unsigned int            sampling_rate;
 
 
         /* Break timer */
@@ -1750,10 +1751,13 @@ static void sci_shutdown(struct uart_port *port)
         sci_free_irq(s);
 }
 
-static unsigned int sci_scbrr_calc(unsigned int algo_id, unsigned int bps,
+static unsigned int sci_scbrr_calc(struct sci_port *s, unsigned int bps,
                                    unsigned long freq)
 {
-        switch (algo_id) {
+        if (s->sampling_rate)
+                return DIV_ROUND_CLOSEST(freq, s->sampling_rate * bps) - 1;
+
+        switch (s->cfg->scbrr_algo_id) {
         case SCBRR_ALGO_1:
                 return freq / (16 * bps);
         case SCBRR_ALGO_2:
@@ -1843,12 +1847,11 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
 
         baud = uart_get_baud_rate(port, termios, old, 0, max_baud);
         if (likely(baud && port->uartclk)) {
-                if (s->cfg->scbrr_algo_id == SCBRR_ALGO_6) {
+                if (s->cfg->type == PORT_HSCIF) {
                         sci_baud_calc_hscif(baud, port->uartclk, &t, &srr,
                                             &cks);
                 } else {
-                        t = sci_scbrr_calc(s->cfg->scbrr_algo_id, baud,
-                                           port->uartclk);
+                        t = sci_scbrr_calc(s, baud, port->uartclk);
                         for (cks = 0; t >= 256 && cks <= 3; cks++)
                                 t >>= 2;
                 }
@@ -2092,6 +2095,7 @@ static int sci_init_single(struct platform_device *dev,
 {
         struct uart_port *port = &sci_port->port;
         const struct resource *res;
+        unsigned int sampling_rate;
         unsigned int i;
         int ret;
 
@@ -2143,28 +2147,47 @@ static int sci_init_single(struct platform_device *dev,
         case PORT_SCIFB:
                 port->fifosize = 256;
                 sci_port->overrun_bit = 9;
+                sampling_rate = 16;
                 break;
         case PORT_HSCIF:
                 port->fifosize = 128;
+                sampling_rate = 0;
                 sci_port->overrun_bit = 0;
                 break;
         case PORT_SCIFA:
                 port->fifosize = 64;
                 sci_port->overrun_bit = 9;
+                sampling_rate = 16;
                 break;
         case PORT_SCIF:
                 port->fifosize = 16;
-                if (p->regtype == SCIx_SH7705_SCIF_REGTYPE)
+                if (p->regtype == SCIx_SH7705_SCIF_REGTYPE) {
                         sci_port->overrun_bit = 9;
-                else
+                        sampling_rate = 16;
+                } else {
                         sci_port->overrun_bit = 0;
+                        sampling_rate = 32;
+                }
                 break;
         default:
                 port->fifosize = 1;
                 sci_port->overrun_bit = 5;
+                sampling_rate = 32;
                 break;
         }
 
+        /* Set the sampling rate if the baud rate calculation algorithm isn't
+         * specified.
+         */
+        if (p->scbrr_algo_id == SCBRR_ALGO_NONE) {
+                /* SCIFA on sh7723 and sh7724 need a custom sampling rate that
+                 * doesn't match the SoC datasheet, this should be investigated.
+                 * Let platform data override the sampling rate for now.
+                 */
+                sci_port->sampling_rate = p->sampling_rate ? p->sampling_rate
+                                        : sampling_rate;
+        }
+
         if (!early) {
                 sci_port->iclk = clk_get(&dev->dev, "sci_ick");
                 if (IS_ERR(sci_port->iclk)) {
diff --git a/include/linux/serial_sci.h b/include/linux/serial_sci.h
index e9c3021a37ae..af414e1895a5 100644
--- a/include/linux/serial_sci.h
+++ b/include/linux/serial_sci.h
@@ -11,6 +11,7 @@
 #define SCIx_NOT_SUPPORTED      (-1)
 
 enum {
+        SCBRR_ALGO_NONE,        /* Compute sampling rate in the driver */
         SCBRR_ALGO_1,           /* clk / (16 * bps) */
         SCBRR_ALGO_2,           /* DIV_ROUND_CLOSEST(clk, 32 * bps) - 1 */
         SCBRR_ALGO_3,           /* clk / (8 * bps) */
@@ -134,6 +135,7 @@ struct plat_sci_port {
         upf_t           flags;                  /* UPF_* flags */
         unsigned long   capabilities;           /* Port features/capabilities */
 
+        unsigned int    sampling_rate;
         unsigned int    scbrr_algo_id;          /* SCBRR calculation algo */
         unsigned int    scscr;                  /* SCSCR initialization */