diff options
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/8250/8250_pci.c | 40 | ||||
| -rw-r--r-- | drivers/tty/serial/8250/Kconfig | 1 |
2 files changed, 10 insertions, 31 deletions
diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c index 495da0643278..7e0519923eb5 100644 --- a/drivers/tty/serial/8250/8250_pci.c +++ b/drivers/tty/serial/8250/8250_pci.c @@ -21,6 +21,7 @@ #include <linux/serial_core.h> #include <linux/8250_pci.h> #include <linux/bitops.h> +#include <linux/rational.h> #include <asm/byteorder.h> #include <asm/io.h> @@ -1393,45 +1394,22 @@ byt_set_termios(struct uart_port *p, struct ktermios *termios, struct ktermios *old) { unsigned int baud = tty_termios_baud_rate(termios); - unsigned int m, n; + unsigned long fref = 100000000, fuart = baud * 16; + unsigned long w = BIT(15) - 1; + unsigned long m, n; u32 reg; + /* Get Fuart closer to Fref */ + fuart *= rounddown_pow_of_two(fref / fuart); + /* * For baud rates 0.5M, 1M, 1.5M, 2M, 2.5M, 3M, 3.5M and 4M the * dividers must be adjusted. * * uartclk = (m / n) * 100 MHz, where m <= n */ - switch (baud) { - case 500000: - case 1000000: - case 2000000: - case 4000000: - m = 64; - n = 100; - p->uartclk = 64000000; - break; - case 3500000: - m = 56; - n = 100; - p->uartclk = 56000000; - break; - case 1500000: - case 3000000: - m = 48; - n = 100; - p->uartclk = 48000000; - break; - case 2500000: - m = 40; - n = 100; - p->uartclk = 40000000; - break; - default: - m = 2304; - n = 3125; - p->uartclk = 73728000; - } + rational_best_approximation(fuart, fref, w, w, &m, &n); + p->uartclk = fuart; /* Reset the clock */ reg = (m << BYT_PRV_CLK_M_VAL_SHIFT) | (n << BYT_PRV_CLK_N_VAL_SHIFT); diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig index 6f7f2d753def..c35070356528 100644 --- a/drivers/tty/serial/8250/Kconfig +++ b/drivers/tty/serial/8250/Kconfig @@ -108,6 +108,7 @@ config SERIAL_8250_PCI tristate "8250/16550 PCI device support" if EXPERT depends on SERIAL_8250 && PCI default SERIAL_8250 + select RATIONAL help This builds standard PCI serial support. You may be able to disable this feature if you only need legacy serial support. |