serial: sh-sci: Rework baud rate calculation

Computing the baud rate register value requires knowledge of the
hardware sampling rate. This information is currently encoded in a baud
rate calculation algorithm ID passed through platform data. However, it
can be derived from the port type directly in most cases.

Compute the sampling rate internally in the driver if the baud rate
calculation algorithm ID isn't specified, and allow platforms to
override the sampling rate through platform data in special cases (this
is only required for SCIFA ports on sh7723 and sh7724, the reason needs
to be investigated).

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

1 files changed, 2 insertions, 0 deletions

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 */