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msm_serial: Make baud_code detection more dynamic

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Currently msm_set_baud_rate() assumes the uart clock rate is
1.8432 MHz. This is not always true, and limits our options to
program the baud rate. Instead of assuming the rate and
hard-coding the baud_code based on it, calculate the divider that
we want and try to find the closest baud_code that matches. This
allows us to support uarts with faster clock speeds.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: David Brown <davidb@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Stephen Boyd 2013-07-24 11:37:30 -07:00 committed by Greg Kroah-Hartman
parent f8fb952fd4
commit 6909dadd91
2 changed files with 48 additions and 68 deletions
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98
drivers/tty/serial/msm_serial.c
View File

@ -322,70 +322,60 @@ static void msm_break_ctl(struct uart_port *port, int break_ctl)
msm_write(port, UART_CR_CMD_STOP_BREAK, UART_CR);
}
struct msm_baud_map {
u16 divisor;
u8 code;
u8 rxstale;
};
static const struct msm_baud_map *
msm_find_best_baud(struct uart_port *port, unsigned int baud)
{
unsigned int i, divisor;
const struct msm_baud_map *entry;
static const struct msm_baud_map table[] = {
{ 1536, 0x00, 1 },
{ 768, 0x11, 1 },
{ 384, 0x22, 1 },
{ 192, 0x33, 1 },
{ 96, 0x44, 1 },
{ 48, 0x55, 1 },
{ 32, 0x66, 1 },
{ 24, 0x77, 1 },
{ 16, 0x88, 1 },
{ 12, 0x99, 6 },
{ 8, 0xaa, 6 },
{ 6, 0xbb, 6 },
{ 4, 0xcc, 6 },
{ 3, 0xdd, 8 },
{ 2, 0xee, 16 },
{ 1, 0xff, 31 },
};
divisor = uart_get_divisor(port, baud);
for (i = 0, entry = table; i < ARRAY_SIZE(table); i++, entry++)
if (entry->divisor <= divisor)
break;
return entry; /* Default to smallest divider */
}
static int msm_set_baud_rate(struct uart_port *port, unsigned int baud)
{
unsigned int baud_code, rxstale, watermark;
unsigned int rxstale, watermark;
struct msm_port *msm_port = UART_TO_MSM(port);
const struct msm_baud_map *entry;
switch (baud) {
case 300:
baud_code = UART_CSR_300;
rxstale = 1;
break;
case 600:
baud_code = UART_CSR_600;
rxstale = 1;
break;
case 1200:
baud_code = UART_CSR_1200;
rxstale = 1;
break;
case 2400:
baud_code = UART_CSR_2400;
rxstale = 1;
break;
case 4800:
baud_code = UART_CSR_4800;
rxstale = 1;
break;
case 9600:
baud_code = UART_CSR_9600;
rxstale = 2;
break;
case 14400:
baud_code = UART_CSR_14400;
rxstale = 3;
break;
case 19200:
baud_code = UART_CSR_19200;
rxstale = 4;
break;
case 28800:
baud_code = UART_CSR_28800;
rxstale = 6;
break;
case 38400:
baud_code = UART_CSR_38400;
rxstale = 8;
break;
case 57600:
baud_code = UART_CSR_57600;
rxstale = 16;
break;
case 115200:
default:
baud_code = UART_CSR_115200;
baud = 115200;
rxstale = 31;
break;
}
entry = msm_find_best_baud(port, baud);
if (msm_port->is_uartdm)
msm_write(port, UART_CR_CMD_RESET_RX, UART_CR);
msm_write(port, baud_code, UART_CSR);
msm_write(port, entry->code, UART_CSR);
/* RX stale watermark */
rxstale = entry->rxstale;
watermark = UART_IPR_STALE_LSB & rxstale;
watermark |= UART_IPR_RXSTALE_LAST;
watermark |= UART_IPR_STALE_TIMEOUT_MSB & (rxstale << 2);

18
drivers/tty/serial/msm_serial.h
View File

@ -38,19 +38,7 @@
#define UART_MR2_PARITY_MODE_SPACE 0x3
#define UART_MR2_PARITY_MODE 0x3
#define UART_CSR 0x0008
#define UART_CSR_115200 0xFF
#define UART_CSR_57600 0xEE
#define UART_CSR_38400 0xDD
#define UART_CSR_28800 0xCC
#define UART_CSR_19200 0xBB
#define UART_CSR_14400 0xAA
#define UART_CSR_9600 0x99
#define UART_CSR_4800 0x77
#define UART_CSR_2400 0x55
#define UART_CSR_1200 0x44
#define UART_CSR_600 0x33
#define UART_CSR_300 0x22
#define UART_CSR 0x0008
#define UART_TF 0x000C
#define UARTDM_TF 0x0070
@ -152,6 +140,7 @@ static inline void msm_serial_set_mnd_regs_tcxo(struct uart_port *port)
msm_write(port, 0xF1, UART_NREG);
msm_write(port, 0x0F, UART_DREG);
msm_write(port, 0x1A, UART_MNDREG);
port->uartclk = 1843200;
}
/*
@ -163,6 +152,7 @@ static inline void msm_serial_set_mnd_regs_tcxoby4(struct uart_port *port)
msm_write(port, 0xF6, UART_NREG);
msm_write(port, 0x0F, UART_DREG);
msm_write(port, 0x0A, UART_MNDREG);
port->uartclk = 1843200;
}
static inline
@ -170,7 +160,7 @@ void msm_serial_set_mnd_regs_from_uartclk(struct uart_port *port)
{
if (port->uartclk == 19200000)
msm_serial_set_mnd_regs_tcxo(port);
else
else if (port->uartclk == 4800000)
msm_serial_set_mnd_regs_tcxoby4(port);
}