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[ARM] S3C: Add UDIVSLOT support for newer UARTS 

Add support for the UDIVSLOT register on the newer UART blocks
which gives the capability of 1/16ths adjustment to the baud rate.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
This commit is contained in:
Ben Dooks 2008-12-12 00:24:21 +00:00
parent 5ef316fbe7
commit 090f848da0
3 changed files with 63 additions and 3 deletions
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1
drivers/serial/s3c6400.c
View File

@ -102,6 +102,7 @@ static struct s3c24xx_uart_info s3c6400_uart_inf = {
.name = "Samsung S3C6400 UART",
.type = PORT_S3C6400,
.fifosize = 64,
.has_divslot = 1,
.rx_fifomask = S3C2440_UFSTAT_RXMASK,
.rx_fifoshift = S3C2440_UFSTAT_RXSHIFT,
.rx_fifofull = S3C2440_UFSTAT_RXFULL,

61
drivers/serial/samsung.c
View File

@ -508,6 +508,7 @@ s3c24xx_serial_setsource(struct uart_port *port, struct s3c24xx_uart_clksrc *c)
struct baud_calc {
struct s3c24xx_uart_clksrc *clksrc;
unsigned int calc;
unsigned int divslot;
unsigned int quot;
struct clk *src;
};
@ -517,6 +518,7 @@ static int s3c24xx_serial_calcbaud(struct baud_calc *calc,
struct s3c24xx_uart_clksrc *clksrc,
unsigned int baud)
{
struct s3c24xx_uart_port *ourport = to_ourport(port);
unsigned long rate;
calc->src = clk_get(port->dev, clksrc->name);
@ -527,8 +529,24 @@ static int s3c24xx_serial_calcbaud(struct baud_calc *calc,
rate /= clksrc->divisor;
calc->clksrc = clksrc;
calc->quot = (rate + (8 * baud)) / (16 * baud);
calc->calc = (rate / (calc->quot * 16));
if (ourport->info->has_divslot) {
unsigned long div = rate / baud;
/* The UDIVSLOT register on the newer UARTs allows us to
* get a divisor adjustment of 1/16th on the baud clock.
*
* We don't keep the UDIVSLOT value (the 16ths we calculated
* by not multiplying the baud by 16) as it is easy enough
* to recalculate.
*/
calc->quot = div / 16;
calc->calc = rate / div;
} else {
calc->quot = (rate + (8 * baud)) / (16 * baud);
calc->calc = (rate / (calc->quot * 16));
}
calc->quot--;
return 1;
@ -611,6 +629,30 @@ static unsigned int s3c24xx_serial_getclk(struct uart_port *port,
return best->quot;
}
/* udivslot_table[]
*
* This table takes the fractional value of the baud divisor and gives
* the recommended setting for the UDIVSLOT register.
*/
static u16 udivslot_table[16] = {
[0] = 0x0000,
[1] = 0x0080,
[2] = 0x0808,
[3] = 0x0888,
[4] = 0x2222,
[5] = 0x4924,
[6] = 0x4A52,
[7] = 0x54AA,
[8] = 0x5555,
[9] = 0xD555,
[10] = 0xD5D5,
[11] = 0xDDD5,
[12] = 0xDDDD,
[13] = 0xDFDD,
[14] = 0xDFDF,
[15] = 0xFFDF,
};
static void s3c24xx_serial_set_termios(struct uart_port *port,
struct ktermios *termios,
struct ktermios *old)
@ -623,6 +665,7 @@ static void s3c24xx_serial_set_termios(struct uart_port *port,
unsigned int baud, quot;
unsigned int ulcon;
unsigned int umcon;
unsigned int udivslot = 0;
/*
* We don't support modem control lines.
@ -644,6 +687,7 @@ static void s3c24xx_serial_set_termios(struct uart_port *port,
/* check to see if we need to change clock source */
if (ourport->clksrc != clksrc || ourport->baudclk != clk) {
dbg("selecting clock %p\n", clk);
s3c24xx_serial_setsource(port, clksrc);
if (ourport->baudclk != NULL && !IS_ERR(ourport->baudclk)) {
@ -658,6 +702,13 @@ static void s3c24xx_serial_set_termios(struct uart_port *port,
ourport->baudclk_rate = clk ? clk_get_rate(clk) : 0;
}
if (ourport->info->has_divslot) {
unsigned int div = ourport->baudclk_rate / baud;
udivslot = udivslot_table[div & 15];
dbg("udivslot = %04x (div %d)\n", udivslot, div & 15);
}
switch (termios->c_cflag & CSIZE) {
case CS5:
dbg("config: 5bits/char\n");
@ -697,12 +748,16 @@ static void s3c24xx_serial_set_termios(struct uart_port *port,
spin_lock_irqsave(&port->lock, flags);
dbg("setting ulcon to %08x, brddiv to %d\n", ulcon, quot);
dbg("setting ulcon to %08x, brddiv to %d, udivslot %08x\n",
ulcon, quot, udivslot);
wr_regl(port, S3C2410_ULCON, ulcon);
wr_regl(port, S3C2410_UBRDIV, quot);
wr_regl(port, S3C2410_UMCON, umcon);
if (ourport->info->has_divslot)
wr_regl(port, S3C2443_DIVSLOT, udivslot);
dbg("uart: ulcon = 0x%08x, ucon = 0x%08x, ufcon = 0x%08x\n",
rd_regl(port, S3C2410_ULCON),
rd_regl(port, S3C2410_UCON),

4
drivers/serial/samsung.h
View File

@ -21,6 +21,10 @@ struct s3c24xx_uart_info {
unsigned long tx_fifoshift;
unsigned long tx_fifofull;
/* uart port features */
unsigned int has_divslot:1;
/* clock source control */
int (*get_clksrc)(struct uart_port *, struct s3c24xx_uart_clksrc *clk);