[ARM] S3C24XX: Support for PWM timer clocks via clk_* API

Add support for the PWM timer clock routing via the
standard clk_ API.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>

arch/arm/plat-s3c24xx/Makefile

@@ -19,6 +19,7 @@ obj-y				+= gpio.o
 obj-y				+= gpiolib.o
 obj-y				+= time.o
 obj-y				+= clock.o
+obj-y				+= pwm-clock.o
 
 # Architecture dependant builds
 

arch/arm/plat-s3c24xx/pwm-clock.c

@@ -0,0 +1,437 @@
+/* linux/arch/arm/plat-s3c24xx/pwm-clock.c
+ *
+ * Copyright (c) 2007 Simtec Electronics
+ * Copyright (c) 2007, 2008 Ben Dooks
+ *	Ben Dooks <ben-linux@fluff.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License.
+*/
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/errno.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+
+#include <asm/hardware.h>
+#include <asm/irq.h>
+
+#include <asm/arch/regs-clock.h>
+#include <asm/arch/regs-gpio.h>
+
+#include <asm/plat-s3c24xx/clock.h>
+#include <asm/plat-s3c24xx/cpu.h>
+
+#include <asm/plat-s3c/regs-timer.h>
+
+/* Each of the timers 0 through 5 go through the following
+ * clock tree, with the inputs depending on the timers.
+ *
+ * pclk ---- [ prescaler 0 ] -+---> timer 0
+ *			      +---> timer 1
+ *
+ * pclk ---- [ prescaler 1 ] -+---> timer 2
+ *			      +---> timer 3
+ *			      \---> timer 4
+ *
+ * Which are fed into the timers as so:
+ *
+ * prescaled 0 ---- [ div 2,4,8,16 ] ---\
+ *				       [mux] -> timer 0
+ * tclk 0 ------------------------------/
+ *
+ * prescaled 0 ---- [ div 2,4,8,16 ] ---\
+ *				       [mux] -> timer 1
+ * tclk 0 ------------------------------/
+ *
+ *
+ * prescaled 1 ---- [ div 2,4,8,16 ] ---\
+ *				       [mux] -> timer 2
+ * tclk 1 ------------------------------/
+ *
+ * prescaled 1 ---- [ div 2,4,8,16 ] ---\
+ *				       [mux] -> timer 3
+ * tclk 1 ------------------------------/
+ *
+ * prescaled 1 ---- [ div 2,4,8, 16 ] --\
+ *				       [mux] -> timer 4
+ * tclk 1 ------------------------------/
+ *
+ * Since the mux and the divider are tied together in the
+ * same register space, it is impossible to set the parent
+ * and the rate at the same time. To avoid this, we add an
+ * intermediate 'prescaled-and-divided' clock to select
+ * as the parent for the timer input clock called tdiv.
+ *
+ * prescaled clk --> pwm-tdiv ---\
+ *                             [ mux ] --> timer X
+ * tclk -------------------------/
+*/
+
+static unsigned long clk_pwm_scaler_getrate(struct clk *clk)
+{
+	unsigned long tcfg0 = __raw_readl(S3C2410_TCFG0);
+
+	if (clk->id == 1) {
+		tcfg0 &= S3C2410_TCFG_PRESCALER1_MASK;
+		tcfg0 >>= S3C2410_TCFG_PRESCALER1_SHIFT;
+	} else {
+		tcfg0 &= S3C2410_TCFG_PRESCALER0_MASK;
+	}
+
+	return clk_get_rate(clk->parent) / (tcfg0 + 1);
+}
+
+/* TODO - add set rate calls. */
+
+struct clk clk_timer_scaler[] = {
+	[0]	= {
+		.name		= "pwm-scaler0",
+		.id		= -1,
+		.get_rate	= clk_pwm_scaler_getrate,
+	},
+	[1]	= {
+		.name		= "pwm-scaler1",
+		.id		= -1,
+		.get_rate	= clk_pwm_scaler_getrate,
+	},
+};
+
+struct clk clk_timer_tclk[] = {
+	[0]	= {
+		.name		= "pwm-tclk0",
+		.id		= -1,
+	},
+	[1]	= {
+		.name		= "pwm-tclk1",
+		.id		= -1,
+	},
+};
+
+struct pwm_tdiv_clk {
+	struct clk	clk;
+	unsigned int	divisor;
+};
+
+static inline struct pwm_tdiv_clk *to_tdiv(struct clk *clk)
+{
+	return container_of(clk, struct pwm_tdiv_clk, clk);
+}
+
+static inline unsigned long tcfg_to_divisor(unsigned long tcfg1)
+{
+	return 1 << (1 + tcfg1);
+}
+
+static unsigned long clk_pwm_tdiv_get_rate(struct clk *clk)
+{
+	unsigned long tcfg1 = __raw_readl(S3C2410_TCFG1);
+	unsigned int divisor;
+
+	tcfg1 >>= S3C2410_TCFG1_SHIFT(clk->id);
+	tcfg1 &= S3C2410_TCFG1_MUX_MASK;
+
+	if (tcfg1 == S3C2410_TCFG1_MUX_TCLK)
+		divisor = to_tdiv(clk)->divisor;
+	else
+		divisor = tcfg_to_divisor(tcfg1);
+
+	return clk_get_rate(clk->parent) / divisor;
+}
+
+static unsigned long clk_pwm_tdiv_round_rate(struct clk *clk,
+					     unsigned long rate)
+{
+	unsigned long parent_rate;
+	unsigned long divisor;
+
+	parent_rate = clk_get_rate(clk->parent);
+	divisor = parent_rate / rate;
+
+	if (divisor <= 2)
+		divisor = 2;
+	else if (divisor <= 4)
+		divisor = 4;
+	else if (divisor <= 8)
+		divisor = 8;
+	else
+		divisor = 16;
+
+	return parent_rate / divisor;
+}
+
+static unsigned long clk_pwm_tdiv_bits(struct pwm_tdiv_clk *divclk)
+{
+	unsigned long bits;
+
+	switch (divclk->divisor) {
+	case 2:
+		bits = S3C2410_TCFG1_MUX_DIV2;
+		break;
+	case 4:
+		bits = S3C2410_TCFG1_MUX_DIV4;
+		break;
+	case 8:
+		bits = S3C2410_TCFG1_MUX_DIV8;
+		break;
+	case 16:
+	default:
+		bits = S3C2410_TCFG1_MUX_DIV16;
+		break;
+	}
+
+	return bits;
+}
+
+static void clk_pwm_tdiv_update(struct pwm_tdiv_clk *divclk)
+{
+	unsigned long tcfg1 = __raw_readl(S3C2410_TCFG1);
+	unsigned long bits = clk_pwm_tdiv_bits(divclk);
+	unsigned long flags;
+	unsigned long shift =  S3C2410_TCFG1_SHIFT(divclk->clk.id);
+
+	local_irq_save(flags);
+
+	tcfg1 = __raw_readl(S3C2410_TCFG1);
+	tcfg1 &= ~(S3C2410_TCFG1_MUX_MASK << shift);
+	tcfg1 |= bits << shift;
+	__raw_writel(tcfg1, S3C2410_TCFG1);
+
+	local_irq_restore(flags);
+}
+
+static int clk_pwm_tdiv_set_rate(struct clk *clk, unsigned long rate)
+{
+	struct pwm_tdiv_clk *divclk = to_tdiv(clk);
+	unsigned long tcfg1 = __raw_readl(S3C2410_TCFG1);
+	unsigned long parent_rate = clk_get_rate(clk->parent);
+	unsigned long divisor;
+
+	tcfg1 >>= S3C2410_TCFG1_SHIFT(clk->id);
+	tcfg1 &= S3C2410_TCFG1_MUX_MASK;
+
+	rate = clk_round_rate(clk, rate);
+	divisor = parent_rate / rate;
+
+	if (divisor > 16)
+		return -EINVAL;
+
+	divclk->divisor = divisor;
+
+	/* Update the current MUX settings if we are currently
+	 * selected as the clock source for this clock. */
+
+	if (tcfg1 != S3C2410_TCFG1_MUX_TCLK)
+		clk_pwm_tdiv_update(divclk);
+
+	return 0;
+}
+
+struct pwm_tdiv_clk clk_timer_tdiv[] = {
+	[0]	= {
+		.clk	= {
+			.name		= "pwm-tdiv",
+			.parent		= &clk_timer_scaler[0],
+			.get_rate	= clk_pwm_tdiv_get_rate,
+			.set_rate	= clk_pwm_tdiv_set_rate,
+			.round_rate	= clk_pwm_tdiv_round_rate,
+		},
+	},
+	[1]	= {
+		.clk	= {
+			.name		= "pwm-tdiv",
+			.parent		= &clk_timer_scaler[0],
+			.get_rate	= clk_pwm_tdiv_get_rate,
+			.set_rate	= clk_pwm_tdiv_set_rate,
+			.round_rate	= clk_pwm_tdiv_round_rate,
+		}
+	},
+	[2]	= {
+		.clk	= {
+			.name		= "pwm-tdiv",
+			.parent		= &clk_timer_scaler[1],
+			.get_rate	= clk_pwm_tdiv_get_rate,
+			.set_rate	= clk_pwm_tdiv_set_rate,
+			.round_rate	= clk_pwm_tdiv_round_rate,
+		},
+	},
+	[3]	= {
+		.clk	= {
+			.name		= "pwm-tdiv",
+			.parent		= &clk_timer_scaler[1],
+			.get_rate	= clk_pwm_tdiv_get_rate,
+			.set_rate	= clk_pwm_tdiv_set_rate,
+			.round_rate	= clk_pwm_tdiv_round_rate,
+		},
+	},
+	[4]	= {
+		.clk	= {
+			.name		= "pwm-tdiv",
+			.parent		= &clk_timer_scaler[1],
+			.get_rate	= clk_pwm_tdiv_get_rate,
+			.set_rate	= clk_pwm_tdiv_set_rate,
+			.round_rate	= clk_pwm_tdiv_round_rate,
+		},
+	},
+};
+
+static int __init clk_pwm_tdiv_register(unsigned int id)
+{
+	struct pwm_tdiv_clk *divclk = &clk_timer_tdiv[id];
+	unsigned long tcfg1 = __raw_readl(S3C2410_TCFG1);
+
+	tcfg1 >>= S3C2410_TCFG1_SHIFT(id);
+	tcfg1 &= S3C2410_TCFG1_MUX_MASK;
+
+	divclk->clk.id = id;
+	divclk->divisor = tcfg_to_divisor(tcfg1);
+
+	return s3c24xx_register_clock(&divclk->clk);
+}
+
+static inline struct clk *s3c24xx_pwmclk_tclk(unsigned int id)
+{
+	return (id >= 2) ? &clk_timer_tclk[1] : &clk_timer_tclk[0];
+}
+
+static inline struct clk *s3c24xx_pwmclk_tdiv(unsigned int id)
+{
+	return &clk_timer_tdiv[id].clk;
+}
+
+static int clk_pwm_tin_set_parent(struct clk *clk, struct clk *parent)
+{
+	unsigned int id = clk->id;
+	unsigned long tcfg1;
+	unsigned long flags;
+	unsigned long bits;
+	unsigned long shift = S3C2410_TCFG1_SHIFT(id);
+
+	if (parent == s3c24xx_pwmclk_tclk(id))
+		bits = S3C2410_TCFG1_MUX_TCLK << shift;
+	else if (parent == s3c24xx_pwmclk_tdiv(id))
+		bits = clk_pwm_tdiv_bits(to_tdiv(clk)) << shift;
+	else
+		return -EINVAL;
+
+	clk->parent = parent;
+
+	local_irq_save(flags);
+
+	tcfg1 = __raw_readl(S3C2410_TCFG1);
+	tcfg1 &= ~(S3C2410_TCFG1_MUX_MASK << shift);
+	__raw_writel(tcfg1 | bits, S3C2410_TCFG1);
+
+	local_irq_restore(flags);
+
+	return 0;
+}
+
+static struct clk clk_tin[] = {
+	[0]	= {
+		.name		= "pwm-tin",
+		.id		= 0,
+		.set_parent	= clk_pwm_tin_set_parent,
+	},
+	[1]	= {
+		.name		= "pwm-tin",
+		.id		= 1,
+		.set_parent	= clk_pwm_tin_set_parent,
+	},
+	[2]	= {
+		.name		= "pwm-tin",
+		.id		= 2,
+		.set_parent	= clk_pwm_tin_set_parent,
+	},
+	[3]	= {
+		.name		= "pwm-tin",
+		.id		= 3,
+		.set_parent	= clk_pwm_tin_set_parent,
+	},
+	[4]	= {
+		.name		= "pwm-tin",
+		.id		= 4,
+		.set_parent	= clk_pwm_tin_set_parent,
+	},
+};
+
+static __init int clk_pwm_tin_register(struct clk *pwm)
+{
+	unsigned long tcfg1 = __raw_readl(S3C2410_TCFG1);
+	unsigned int id = pwm->id;
+
+	struct clk *parent;
+	int ret;
+
+	ret = s3c24xx_register_clock(pwm);
+	if (ret < 0)
+		return ret;
+
+	tcfg1 >>= S3C2410_TCFG1_SHIFT(id);
+	tcfg1 &= S3C2410_TCFG1_MUX_MASK;
+
+	if (tcfg1 == S3C2410_TCFG1_MUX_TCLK)
+		parent = s3c24xx_pwmclk_tclk(id);
+	else
+		parent = s3c24xx_pwmclk_tdiv(id);
+
+	return clk_set_parent(pwm, parent);
+}
+
+static __init int s3c24xx_pwmclk_init(void)
+{
+	struct clk *clk_timers;
+	unsigned int clk;
+	int ret;
+
+	clk_timers = clk_get(NULL, "timers");
+	if (IS_ERR(clk_timers)) {
+		printk(KERN_ERR "%s: no parent clock\n", __func__);
+		return -EINVAL;
+	}
+
+	for (clk = 0; clk < ARRAY_SIZE(clk_timer_scaler); clk++) {
+		clk_timer_scaler[clk].parent = clk_timers;
+		ret = s3c24xx_register_clock(&clk_timer_scaler[clk]);
+		if (ret < 0) {
+			printk(KERN_ERR "error adding pwm scaler%d clock\n", clk);
+			goto err;
+		}
+	}
+
+	for (clk = 0; clk < ARRAY_SIZE(clk_timer_tclk); clk++) {
+		ret = s3c24xx_register_clock(&clk_timer_tclk[clk]);
+		if (ret < 0) {
+			printk(KERN_ERR "error adding pww tclk%d\n", clk);
+			goto err;
+		}
+	}
+
+	for (clk = 0; clk < ARRAY_SIZE(clk_timer_tdiv); clk++) {
+		ret = clk_pwm_tdiv_register(clk);
+		if (ret < 0) {
+			printk(KERN_ERR "error adding pwm%d tdiv clock\n", clk);
+			goto err;
+		}
+	}
+
+	for (clk = 0; clk < ARRAY_SIZE(clk_tin); clk++) {
+		ret = clk_pwm_tin_register(&clk_tin[clk]);
+		if (ret < 0) {
+			printk(KERN_ERR "error adding pwm%d tin clock\n", clk);
+			goto err;
+		}
+	}
+
+	return 0;
+
+ err:
+	return ret;
+}
+
+arch_initcall(s3c24xx_pwmclk_init);