Commit 6e1e48b6 authored by Tudor Ambarus's avatar Tudor Ambarus Committed by Greg Kroah-Hartman
Browse files

tty: serial: samsung: shrink the clock selection to 8 clocks 



<linux/serial_s3c.h> provides a clock selection pool of maximum 4 clocks.
Update the driver to consider a pool selection of maximum 8 clocks.
u8 is large enough to allow more clocks than are supported by the driver
now, and not too big to cause spanning of ``struct s3c24xx_uart_info``
through 2 cachelines when compiled for arm64. The goal is to reduce the
memory footprint of ``struct s3c24xx_uart_info``.

Reviewed-by: default avatarSam Protsenko <semen.protsenko@linaro.org>
Signed-off-by: default avatarTudor Ambarus <tudor.ambarus@linaro.org>
Link: https://lore.kernel.org/r/20240119104526.1221243-18-tudor.ambarus@linaro.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 92e32ed3

drivers/tty/serial/samsung_tty.c

+11 −11
Original line number Diff line number Diff line
@@ -81,11 +81,11 @@ struct s3c24xx_uart_info { 
	unsigned long		tx_fifomask;

	unsigned long		tx_fifoshift;

	unsigned long		tx_fifofull;

	unsigned int		def_clk_sel;

	unsigned long		num_clks;

	unsigned long		clksel_mask;

	unsigned long		clksel_shift;

	unsigned long		ucon_mask;

	u8			def_clk_sel;

	u8			num_clks;

	u8			iotype;



	/* uart port features */
@@ -1340,7 +1340,7 @@ static void s3c24xx_serial_pm(struct uart_port *port, unsigned int level, 


#define MAX_CLK_NAME_LENGTH 15



static inline int s3c24xx_serial_getsource(struct uart_port *port)

static inline u8 s3c24xx_serial_getsource(struct uart_port *port)

{

	const struct s3c24xx_uart_info *info = s3c24xx_port_to_info(port);

	u32 ucon;
@@ -1353,8 +1353,7 @@ static inline int s3c24xx_serial_getsource(struct uart_port *port) 
	return ucon >> info->clksel_shift;

}



static void s3c24xx_serial_setsource(struct uart_port *port,

			unsigned int clk_sel)

static void s3c24xx_serial_setsource(struct uart_port *port, u8 clk_sel)

{

	const struct s3c24xx_uart_info *info = s3c24xx_port_to_info(port);

	u32 ucon;
@@ -1373,14 +1372,15 @@ static void s3c24xx_serial_setsource(struct uart_port *port, 


static unsigned int s3c24xx_serial_getclk(struct s3c24xx_uart_port *ourport,

			unsigned int req_baud, struct clk **best_clk,

			unsigned int *clk_num)

			u8 *clk_num)

{

	const struct s3c24xx_uart_info *info = ourport->info;

	struct clk *clk;

	unsigned long rate;

	unsigned int cnt, baud, quot, best_quot = 0;

	unsigned int baud, quot, best_quot = 0;

	char clkname[MAX_CLK_NAME_LENGTH];

	int calc_deviation, deviation = (1 << 30) - 1;

	u8 cnt;



	for (cnt = 0; cnt < info->num_clks; cnt++) {

		/* Keep selected clock if provided */
@@ -1473,9 +1473,10 @@ static void s3c24xx_serial_set_termios(struct uart_port *port, 
	struct s3c24xx_uart_port *ourport = to_ourport(port);

	struct clk *clk = ERR_PTR(-EINVAL);

	unsigned long flags;

	unsigned int baud, quot, clk_sel = 0;

	unsigned int baud, quot;

	unsigned int udivslot = 0;

	u32 ulcon, umcon;

	u8 clk_sel = 0;



	/*

	 * We don't support modem control lines.
@@ -1776,10 +1777,9 @@ static int s3c24xx_serial_enable_baudclk(struct s3c24xx_uart_port *ourport) 
	struct device *dev = ourport->port.dev;

	const struct s3c24xx_uart_info *info = ourport->info;

	char clk_name[MAX_CLK_NAME_LENGTH];

	unsigned int clk_sel;

	struct clk *clk;

	int clk_num;

	int ret;

	u8 clk_sel, clk_num;



	clk_sel = ourport->cfg->clk_sel ? : info->def_clk_sel;

	for (clk_num = 0; clk_num < info->num_clks; clk_num++) {
@@ -2287,9 +2287,9 @@ s3c24xx_serial_get_options(struct uart_port *port, int *baud, 
{

	struct clk *clk;

	unsigned long rate;

	unsigned int clk_sel;

	u32 ulcon, ucon, ubrdiv;

	char clk_name[MAX_CLK_NAME_LENGTH];

	u8 clk_sel;



	ulcon  = rd_regl(port, S3C2410_ULCON);

	ucon   = rd_regl(port, S3C2410_UCON);