[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>

2 files changed, 438 insertions, 0 deletions

diff --git a/arch/arm/plat-s3c24xx/Makefile b/arch/arm/plat-s3c24xx/Makefile
index b91e62585684..c925d577fef4 100644
--- a/arch/arm/plat-s3c24xx/Makefile
+++ b/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
 
diff --git a/arch/arm/plat-s3c24xx/pwm-clock.c b/arch/arm/plat-s3c24xx/pwm-clock.c
new file mode 100644
index 000000000000..2cda3e3c6786
--- /dev/null
+++ b/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);