[ARM] S3C24XX: PWM API support.

Add support for PWM in the S3C24XX series of SoC via the
PWM API.

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

1 files changed, 402 insertions, 0 deletions

diff --git a/arch/arm/plat-s3c24xx/pwm.c b/arch/arm/plat-s3c24xx/pwm.c
new file mode 100644
index 000000000000..18c4bdc49a05
--- /dev/null
+++ b/arch/arm/plat-s3c24xx/pwm.c
@@ -0,0 +1,402 @@
+/* arch/arm/plat-s3c24xx/pwm.c
+ *
+ * Copyright (c) 2007 Ben Dooks
+ * Copyright (c) 2008 Simtec Electronics
+ *      Ben Dooks <ben@simtec.co.uk>, <ben-linux@fluff.org>
+ *
+ * S3C24XX PWM device core
+ *
+ * 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/module.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/pwm.h>
+
+#include <asm/plat-s3c/regs-timer.h>
+
+struct pwm_device {
+        struct list_head         list;
+        struct platform_device  *pdev;
+
+        struct clk              *clk_div;
+        struct clk              *clk;
+        const char              *label;
+
+        unsigned int             period_ns;
+        unsigned int             duty_ns;
+
+        unsigned char            tcon_base;
+        unsigned char            running;
+        unsigned char            use_count;
+        unsigned char            pwm_id;
+};
+
+#define pwm_dbg(_pwm, msg...) dev_info(&(_pwm)->pdev->dev, msg)
+
+static struct clk *clk_scaler[2];
+
+/* Standard setup for a timer block. */
+
+#define TIMER_RESOURCE_SIZE (1)
+
+#define TIMER_RESOURCE(_tmr, _irq)                      \
+        (struct resource [TIMER_RESOURCE_SIZE]) {       \
+                [0] = {                                 \
+                        .start  = _irq,                 \
+                        .end    = _irq,                 \
+                        .flags  = IORESOURCE_IRQ        \
+                }                                       \
+        }
+
+#define DEFINE_TIMER(_tmr_no, _irq)                     \
+        .name           = "s3c24xx-pwm",                \
+        .id             = _tmr_no,                      \
+        .num_resources  = TIMER_RESOURCE_SIZE,          \
+        .resource       = TIMER_RESOURCE(_tmr_no, _irq),        \
+
+/* since we already have an static mapping for the timer, we do not
+ * bother setting any IO resource for the base.
+ */
+
+struct platform_device s3c_device_timer[] = {
+        [0] = { DEFINE_TIMER(0, IRQ_TIMER0) },
+        [1] = { DEFINE_TIMER(1, IRQ_TIMER1) },
+        [2] = { DEFINE_TIMER(2, IRQ_TIMER2) },
+        [3] = { DEFINE_TIMER(3, IRQ_TIMER3) },
+        [4] = { DEFINE_TIMER(4, IRQ_TIMER4) },
+};
+
+static inline int pwm_is_tdiv(struct pwm_device *pwm)
+{
+        return clk_get_parent(pwm->clk) == pwm->clk_div;
+}
+
+static DEFINE_MUTEX(pwm_lock);
+static LIST_HEAD(pwm_list);
+
+struct pwm_device *pwm_request(int pwm_id, const char *label)
+{
+        struct pwm_device *pwm;
+        int found = 0;
+
+        mutex_lock(&pwm_lock);
+
+        list_for_each_entry(pwm, &pwm_list, list) {
+                if (pwm->pwm_id == pwm_id) {
+                        found = 1;
+                        break;
+                }
+        }
+
+        if (found) {
+                if (pwm->use_count == 0) {
+                        pwm->use_count = 1;
+                        pwm->label = label;
+                } else
+                        pwm = ERR_PTR(-EBUSY);
+        } else
+                pwm = ERR_PTR(-ENOENT);
+
+        mutex_unlock(&pwm_lock);
+        return pwm;
+}
+
+EXPORT_SYMBOL(pwm_request);
+
+
+void pwm_free(struct pwm_device *pwm)
+{
+        mutex_lock(&pwm_lock);
+
+        if (pwm->use_count) {
+                pwm->use_count--;
+                pwm->label = NULL;
+        } else
+                printk(KERN_ERR "PWM%d device already freed\n", pwm->pwm_id);
+
+        mutex_unlock(&pwm_lock);
+}
+
+EXPORT_SYMBOL(pwm_free);
+
+#define pwm_tcon_start(pwm) (1 << (pwm->tcon_base + 0))
+#define pwm_tcon_invert(pwm) (1 << (pwm->tcon_base + 2))
+#define pwm_tcon_autoreload(pwm) (1 << (pwm->tcon_base + 3))
+#define pwm_tcon_manulupdate(pwm) (1 << (pwm->tcon_base + 1))
+
+int pwm_enable(struct pwm_device *pwm)
+{
+        unsigned long flags;
+        unsigned long tcon;
+
+        local_irq_save(flags);
+
+        tcon = __raw_readl(S3C2410_TCON);
+        tcon |= pwm_tcon_start(pwm);
+        __raw_writel(tcon, S3C2410_TCON);
+
+        local_irq_restore(flags);
+
+        pwm->running = 1;
+        return 0;
+}
+
+EXPORT_SYMBOL(pwm_enable);
+
+void pwm_disable(struct pwm_device *pwm)
+{
+        unsigned long flags;
+        unsigned long tcon;
+
+        local_irq_save(flags);
+
+        tcon = __raw_readl(S3C2410_TCON);
+        tcon &= ~pwm_tcon_start(pwm);
+        __raw_writel(tcon, S3C2410_TCON);
+
+        local_irq_restore(flags);
+
+        pwm->running = 0;
+}
+
+EXPORT_SYMBOL(pwm_disable);
+
+unsigned long pwm_calc_tin(struct pwm_device *pwm, unsigned long freq)
+{
+        unsigned long tin_parent_rate;
+        unsigned int div;
+
+        tin_parent_rate = clk_get_rate(clk_get_parent(pwm->clk_div));
+        pwm_dbg(pwm, "tin parent at %lu\n", tin_parent_rate);
+
+        for (div = 2; div <= 16; div *= 2) {
+                if ((tin_parent_rate / (div << 16)) < freq)
+                        return tin_parent_rate / div;
+        }
+
+        return tin_parent_rate / 16;
+}
+
+#define NS_IN_HZ (1000000000UL)
+
+int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
+{
+        unsigned long tin_rate;
+        unsigned long tin_ns;
+        unsigned long period;
+        unsigned long flags;
+        unsigned long tcon;
+        unsigned long tcnt;
+        long tcmp;
+
+        /* We currently avoid using 64bit arithmetic by using the
+         * fact that anything faster than 1Hz is easily representable
+         * by 32bits. */
+
+        if (period_ns > NS_IN_HZ || duty_ns > NS_IN_HZ)
+                return -ERANGE;
+
+        if (duty_ns > period_ns)
+                return -EINVAL;
+
+        if (period_ns == pwm->period_ns &&
+            duty_ns == pwm->duty_ns)
+                return 0;
+
+        /* The TCMP and TCNT can be read without a lock, they're not
+         * shared between the timers. */
+
+        tcmp = __raw_readl(S3C2410_TCMPB(pwm->pwm_id));
+        tcnt = __raw_readl(S3C2410_TCNTB(pwm->pwm_id));
+
+        period = NS_IN_HZ / period_ns;
+
+        pwm_dbg(pwm, "duty_ns=%d, period_ns=%d (%lu)\n",
+                duty_ns, period_ns, period);
+
+        /* Check to see if we are changing the clock rate of the PWM */
+
+        if (pwm->period_ns != period_ns) {
+                if (pwm_is_tdiv(pwm)) {
+                        tin_rate = pwm_calc_tin(pwm, period);
+                        clk_set_rate(pwm->clk_div, tin_rate);
+                } else
+                        tin_rate = clk_get_rate(pwm->clk);
+
+                pwm->period_ns = period_ns;
+
+                pwm_dbg(pwm, "tin_rate=%lu\n", tin_rate);
+
+                tin_ns = NS_IN_HZ / tin_rate;
+                tcnt = period_ns / tin_ns;
+        } else
+                tin_ns = NS_IN_HZ / clk_get_rate(pwm->clk);
+
+        /* Note, counters count down */
+
+        tcmp = duty_ns / tin_ns;
+        tcmp = tcnt - tcmp;
+
+        pwm_dbg(pwm, "tin_ns=%lu, tcmp=%ld/%lu\n", tin_ns, tcmp, tcnt);
+
+        if (tcmp < 0)
+                tcmp = 0;
+
+        /* Update the PWM register block. */
+
+        local_irq_save(flags);
+
+        __raw_writel(tcmp, S3C2410_TCMPB(pwm->pwm_id));
+        __raw_writel(tcnt, S3C2410_TCNTB(pwm->pwm_id));
+
+        tcon = __raw_readl(S3C2410_TCON);
+        tcon |= pwm_tcon_manulupdate(pwm);
+        tcon |= pwm_tcon_autoreload(pwm);
+        __raw_writel(tcon, S3C2410_TCON);
+
+        tcon &= ~pwm_tcon_manulupdate(pwm);
+        __raw_writel(tcon, S3C2410_TCON);
+
+        local_irq_restore(flags);
+
+        return 0;
+}
+
+EXPORT_SYMBOL(pwm_config);
+
+static int pwm_register(struct pwm_device *pwm)
+{
+        pwm->duty_ns = -1;
+        pwm->period_ns = -1;
+
+        mutex_lock(&pwm_lock);
+        list_add_tail(&pwm->list, &pwm_list);
+        mutex_unlock(&pwm_lock);
+
+        return 0;
+}
+
+static int s3c_pwm_probe(struct platform_device *pdev)
+{
+        struct device *dev = &pdev->dev;
+        struct pwm_device *pwm;
+        unsigned long flags;
+        unsigned long tcon;
+        unsigned int id = pdev->id;
+        int ret;
+
+        if (id == 4) {
+                dev_err(dev, "TIMER4 is currently not supported\n");
+                return -ENXIO;
+        }
+
+        pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
+        if (pwm == NULL) {
+                dev_err(dev, "failed to allocate pwm_device\n");
+                return -ENOMEM;
+        }
+
+        pwm->pdev = pdev;
+        pwm->pwm_id = id;
+
+        /* calculate base of control bits in TCON */
+        pwm->tcon_base = id == 0 ? 0 : (id * 4) + 4;
+
+        pwm->clk = clk_get(dev, "pwm-tin");
+        if (IS_ERR(pwm->clk)) {
+                dev_err(dev, "failed to get pwm tin clk\n");
+                ret = PTR_ERR(pwm->clk);
+                goto err_alloc;
+        }
+
+        pwm->clk_div = clk_get(dev, "pwm-tdiv");
+        if (IS_ERR(pwm->clk_div)) {
+                dev_err(dev, "failed to get pwm tdiv clk\n");
+                ret = PTR_ERR(pwm->clk_div);
+                goto err_clk_tin;
+        }
+
+        local_irq_save(flags);
+
+        tcon = __raw_readl(S3C2410_TCON);
+        tcon |= pwm_tcon_invert(pwm);
+        __raw_writel(tcon, S3C2410_TCON);
+
+        local_irq_restore(flags);
+
+
+        ret = pwm_register(pwm);
+        if (ret) {
+                dev_err(dev, "failed to register pwm\n");
+                goto err_clk_tdiv;
+        }
+
+        pwm_dbg(pwm, "config bits %02x\n",
+                (__raw_readl(S3C2410_TCON) >> pwm->tcon_base) & 0x0f);
+
+        dev_info(dev, "tin at %lu, tdiv at %lu, tin=%sclk, base %d\n",
+                 clk_get_rate(pwm->clk),
+                 clk_get_rate(pwm->clk_div),
+                 pwm_is_tdiv(pwm) ? "div" : "ext", pwm->tcon_base);
+
+        platform_set_drvdata(pdev, pwm);
+        return 0;
+
+ err_clk_tdiv:
+        clk_put(pwm->clk_div);
+
+ err_clk_tin:
+        clk_put(pwm->clk);
+
+ err_alloc:
+        kfree(pwm);
+        return ret;
+}
+
+static int s3c_pwm_remove(struct platform_device *pdev)
+{
+        struct pwm_device *pwm = platform_get_drvdata(pdev);
+
+        clk_put(pwm->clk_div);
+        clk_put(pwm->clk);
+        kfree(pwm);
+
+        return 0;
+}
+
+static struct platform_driver s3c_pwm_driver = {
+        .driver         = {
+                .name   = "s3c24xx-pwm",
+                .owner  = THIS_MODULE,
+        },
+        .probe          = s3c_pwm_probe,
+        .remove         = __devexit_p(s3c_pwm_remove),
+};
+
+static int __init pwm_init(void)
+{
+        int ret;
+
+        clk_scaler[0] = clk_get(NULL, "pwm-scaler0");
+        clk_scaler[1] = clk_get(NULL, "pwm-scaler1");
+
+        if (IS_ERR(clk_scaler[0]) || IS_ERR(clk_scaler[1])) {
+                printk(KERN_ERR "%s: failed to get scaler clocks\n", __func__);
+                return -EINVAL;
+        }
+
+        ret = platform_driver_register(&s3c_pwm_driver);
+        if (ret)
+                printk(KERN_ERR "%s: failed to add pwm driver\n", __func__);
+
+        return ret;
+}
+
+arch_initcall(pwm_init);