[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 0000000..18c4bdc
--- /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);