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serial: sh-sci: Rework baud rate calculation

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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>
This commit is contained in:
Laurent Pinchart 2013-12-06 10:59:20 +01:00 • committed by Simon Horman
parent b545e4f406
commit ec09c5eb49
2 changed files with 32 additions and 7 deletions
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2
include/linux/serial_sci.h
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@ -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 */