[PATCH 10/14] MACH SAMSUNG/S3C: Re-work the S3C family timer driver

[Juergen Beisert]

After separation and after all S3C macros are now present, change the driver
to be more generic for future additions. This includes the clock sources of
the timers, that will be now in the CPU part (it cannot be generic due to
differences in the clock tree).

The timer registers in the S3C24XX family are only 16 bit wide. But these
registers can be read and written in a 32 bit manner.

Signed-off-by: Juergen Beisert <jbe at pengutronix.de>
---
 arch/arm/mach-samsung/include/mach/s3c-generic.h |    3 +
 arch/arm/mach-samsung/include/mach/s3c-timer.h   |   10 ++++
 arch/arm/mach-samsung/s3c-timer.c                |   54 ++++++++++++++-------
 arch/arm/mach-samsung/s3c24xx-clocks.c           |   24 ++++++++++
 4 files changed, 73 insertions(+), 18 deletions(-)

diff --git a/arch/arm/mach-samsung/include/mach/s3c-generic.h b/arch/arm/mach-samsung/include/mach/s3c-generic.h
index 33f025d..0909c0e 100644
--- a/arch/arm/mach-samsung/include/mach/s3c-generic.h
+++ b/arch/arm/mach-samsung/include/mach/s3c-generic.h
@@ -30,4 +30,7 @@ uint32_t s3c_get_fclk(void);
 uint32_t s3c_get_hclk(void);
 uint32_t s3c_get_pclk(void);
 uint32_t s3c_get_uclk(void);
+void s3c_init_t4_clk_source(void);
+unsigned s3c_get_t4_clk(void);
 uint32_t s3c24x0_get_memory_size(void);
+
diff --git a/arch/arm/mach-samsung/include/mach/s3c-timer.h b/arch/arm/mach-samsung/include/mach/s3c-timer.h
index 5201fc4..f122b09 100644
--- a/arch/arm/mach-samsung/include/mach/s3c-timer.h
+++ b/arch/arm/mach-samsung/include/mach/s3c-timer.h
@@ -16,8 +16,18 @@
 # define __MACH_S3C_TIMER_H
 
 #define S3C_TCFG0 (S3C_TIMER_BASE + 0x00)
+# define S3C_TCFG0_T4MASK 0xff00
+# define S3C_TCFG0_SET_PSCL234(x) ((x) << 8)
+# define S3C_TCFG0_GET_PSCL234(x) (((x) >> 8) & 0xff)
 #define S3C_TCFG1 (S3C_TIMER_BASE + 0x04)
+# define S3C_TCFG1_T4MASK 0xf0000
+# define S3C_TCFG1_SET_T4MUX(x) ((x) << 16)
+# define S3C_TCFG1_GET_T4MUX(x) (((x) >> 16) & 0xf)
 #define S3C_TCON (S3C_TIMER_BASE + 0x08)
+# define S3C_TCON_T4MASK (7 << 20)
+# define S3C_TCON_T4START (1 << 20)
+# define S3C_TCON_T4MANUALUPD (1 << 21)
+# define S3C_TCON_T4RELOAD (1 <<22)
 #define S3C_TCNTB0 (S3C_TIMER_BASE + 0x0c)
 #define S3C_TCMPB0 (S3C_TIMER_BASE + 0x10)
 #define S3C_TCNTO0 (S3C_TIMER_BASE + 0x14)
diff --git a/arch/arm/mach-samsung/s3c-timer.c b/arch/arm/mach-samsung/s3c-timer.c
index a3ce4a2..a29c8d6 100644
--- a/arch/arm/mach-samsung/s3c-timer.c
+++ b/arch/arm/mach-samsung/s3c-timer.c
@@ -22,35 +22,53 @@
 #include <mach/s3c-generic.h>
 #include <mach/s3c-timer.h>
 
-static uint64_t s3c24xx_clocksource_read(void)
+#define TIMER_WIDTH 16
+#define TIMER_SHIFT 10
+static const uint32_t max = 0x0000ffff;
+
+static void s3c_timer_init(void)
+{
+	unsigned tcon;
+
+	tcon = readl(S3C_TCON) & ~S3C_TCON_T4MASK;
+
+	writel(max, S3C_TCNTB4);	/* reload value */
+	/* force a manual counter update */
+	writel(tcon | S3C_TCON_T4MANUALUPD, S3C_TCON);
+}
+
+static void s3c_timer_start(void)
+{
+	unsigned tcon;
+
+	tcon  = readl(S3C_TCON) & ~S3C_TCON_T4MANUALUPD;
+	tcon |= S3C_TCON_T4START | S3C_TCON_T4RELOAD;
+	writel(tcon, S3C_TCON);
+}
+
+static uint64_t s3c_clocksource_read(void)
 {
 	/* note: its a down counter */
-	return 0xFFFF - readw(S3C_TCNTO4);
+	return max - readl(S3C_TCNTO4);
 }
 
 static struct clocksource cs = {
-	.read	= s3c24xx_clocksource_read,
-	.mask	= CLOCKSOURCE_MASK(16),
-	.shift	= 10,
+	.read = s3c_clocksource_read,
+	.mask = CLOCKSOURCE_MASK(TIMER_WIDTH),
+	.shift = TIMER_SHIFT,
 };
 
-static int clocksource_init(void)
+static int s3c_clk_src_init(void)
 {
-	uint32_t p_clk = s3c_get_pclk();
-
-	writel(0x00000000, S3C_TCON);	/* stop all timers */
-	writel(0x00ffffff, S3C_TCFG0);	/* PCLK / (255 + 1) for timer 4 */
-	writel(0x00030000, S3C_TCFG1);	/* /16 */
-
-	writew(0xffff, S3C_TCNTB4);	/* reload value is TOP */
+	/* select its clock source first */
+	s3c_init_t4_clk_source();
 
-	writel(0x00600000, S3C_TCON);	/* force a first reload */
-	writel(0x00400000, S3C_TCON);
-	writel(0x00500000, S3C_TCON);	/* enable timer 4 with auto reload */
+	s3c_timer_init();
+	s3c_timer_start();
 
-	cs.mult = clocksource_hz2mult(p_clk / ((255 + 1) * 16), cs.shift);
+	cs.mult = clocksource_hz2mult(s3c_get_t4_clk(), cs.shift);
 	init_clock(&cs);
 
 	return 0;
 }
-core_initcall(clocksource_init);
+core_initcall(s3c_clk_src_init);
diff --git a/arch/arm/mach-samsung/s3c24xx-clocks.c b/arch/arm/mach-samsung/s3c24xx-clocks.c
index beacc76..3a230b2 100644
--- a/arch/arm/mach-samsung/s3c24xx-clocks.c
+++ b/arch/arm/mach-samsung/s3c24xx-clocks.c
@@ -21,6 +21,7 @@
 #include <mach/s3c-iomap.h>
 #include <mach/s3c-generic.h>
 #include <mach/s3c-clocks.h>
+#include <mach/s3c-timer.h>
 
 /**
  * Calculate the current M-PLL clock.
@@ -116,6 +117,29 @@ uint32_t s3c24_get_uclk(void)
 	return s3c_get_upllclk();
 }
 
+void s3c_init_t4_clk_source(void)
+{
+	unsigned reg;
+
+	reg = readl(S3C_TCON) & ~S3C_TCON_T4MASK; /* stop timer 4 */
+	writel(reg, S3C_TCON);
+	reg = readl(S3C_TCFG0) & ~S3C_TCFG0_T4MASK;
+	reg |= S3C_TCFG0_SET_PSCL234(0); /* 0 means pre scaler is '256' */
+	writel(reg, S3C_TCFG0);
+	reg = readl(S3C_TCFG1) & ~S3C_TCFG1_T4MASK;
+	reg |= S3C_TCFG1_SET_T4MUX(3); /* / 16 */
+	writel(reg, S3C_TCFG1);
+}
+
+unsigned s3c_get_t4_clk(void)
+{
+	unsigned clk = s3c_get_pclk();
+	unsigned pre = S3C_TCFG0_GET_PSCL234(readl(S3C_TCFG0)) + 1;
+	unsigned div = S3C_TCFG1_GET_T4MUX(readl(S3C_TCFG1)) + 1;
+
+	return clk / pre / (1 << div);
+}
+
 /**
  * Show the user the current clock settings
  */
-- 
1.7.7.1