[ARM] pxa: Add PXA support for PWM API

Patch mainly from Eric Miao, with minor edits by rmk.

Note: PWM0 and PWM2 share the same register I/O space and clock gating
on pxa{27x, 3xx}, thus PWM2 is treated in the driver as a child PWM of
PWM0. And this is also true for PWM1/3.

Signed-off-by: eric miao <eric.miao@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 299 insertions, 0 deletions

diff --git a/arch/arm/mach-pxa/pwm.c b/arch/arm/mach-pxa/pwm.c
new file mode 100644
index 000000000000..70fb3ca6a058
--- /dev/null
+++ b/arch/arm/mach-pxa/pwm.c
@@ -0,0 +1,299 @@
+/*
+ * linux/arch/arm/mach-pxa/pwm.c
+ *
+ * simple driver for PWM (Pulse Width Modulator) controller
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * 2008-02-13	initial version
+ * 		eric miao <eric.miao@marvell.com>
+ */
+
+#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/div64.h>
+#include <asm/arch/pxa-regs.h>
+
+/* PWM registers and bits definitions */
+#define PWMCR		(0x00)
+#define PWMDCR		(0x04)
+#define PWMPCR		(0x08)
+
+#define PWMCR_SD	(1 << 6)
+#define PWMDCR_FD	(1 << 10)
+
+struct pwm_device {
+	struct list_head	node;
+	struct platform_device *pdev;
+
+	const char	*label;
+	struct clk	*clk;
+	void __iomem	*mmio_base;
+
+	unsigned int	use_count;
+	unsigned int	pwm_id;
+};
+
+/*
+ * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
+ * duty_ns   = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
+ */
+int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
+{
+	unsigned long long c;
+	unsigned long period_cycles, prescale, pv, dc;
+
+	if (pwm == NULL || period_ns == 0 || duty_ns > period_ns)
+		return -EINVAL;
+
+	c = clk_get_rate(pwm->clk);
+	c = c * period_ns;
+	do_div(c, 1000000000);
+	period_cycles = c;
+
+	if (period_cycles < 0)
+		period_cycles = 1;
+	prescale = (period_cycles - 1) / 1024;
+	pv = period_cycles / (prescale + 1) - 1;
+
+	if (prescale > 63)
+		return -EINVAL;
+
+	if (duty_ns == period_ns)
+		dc = PWMDCR_FD;
+	else
+		dc = (pv + 1) * duty_ns / period_ns;
+
+	/* NOTE: the clock to PWM has to be enabled first
+	 * before writing to the registers
+	 */
+	clk_enable(pwm->clk);
+	__raw_writel(prescale, pwm->mmio_base + PWMCR);
+	__raw_writel(dc, pwm->mmio_base + PWMDCR);
+	__raw_writel(pv, pwm->mmio_base + PWMPCR);
+	clk_disable(pwm->clk);
+
+	return 0;
+}
+EXPORT_SYMBOL(pwm_config);
+
+int pwm_enable(struct pwm_device *pwm)
+{
+	return clk_enable(pwm->clk);
+}
+EXPORT_SYMBOL(pwm_enable);
+
+void pwm_disable(struct pwm_device *pwm)
+{
+	clk_disable(pwm->clk);
+}
+EXPORT_SYMBOL(pwm_disable);
+
+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, node) {
+		if (pwm->pwm_id == pwm_id && pwm->use_count == 0) {
+			pwm->use_count++;
+			pwm->label = label;
+			found = 1;
+			break;
+		}
+	}
+
+	mutex_unlock(&pwm_lock);
+
+	return (found) ? pwm : NULL;
+}
+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
+		pr_warning("PWM device already freed\n");
+
+	mutex_unlock(&pwm_lock);
+}
+EXPORT_SYMBOL(pwm_free);
+
+static inline void __add_pwm(struct pwm_device *pwm)
+{
+	mutex_lock(&pwm_lock);
+	list_add_tail(&pwm->node, &pwm_list);
+	mutex_unlock(&pwm_lock);
+}
+
+static struct pwm_device *pwm_probe(struct platform_device *pdev,
+		unsigned int pwm_id, struct pwm_device *parent_pwm)
+{
+	struct pwm_device *pwm;
+	struct resource *r;
+	int ret = 0;
+
+	pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
+	if (pwm == NULL) {
+		dev_err(&pdev->dev, "failed to allocate memory\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	pwm->clk = clk_get(&pdev->dev, "PWMCLK");
+	if (IS_ERR(pwm->clk)) {
+		ret = PTR_ERR(pwm->clk);
+		goto err_free;
+	}
+
+	pwm->use_count = 0;
+	pwm->pwm_id = pwm_id;
+	pwm->pdev = pdev;
+
+	if (parent_pwm != NULL) {
+		/* registers for the second PWM has offset of 0x10 */
+		pwm->mmio_base = parent_pwm->mmio_base + 0x10;
+		__add_pwm(pwm);
+		return pwm;
+	}
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (r == NULL) {
+		dev_err(&pdev->dev, "no memory resource defined\n");
+		ret = -ENODEV;
+		goto err_free_clk;
+	}
+
+	r = request_mem_region(r->start, r->end - r->start + 1, pdev->name);
+	if (r == NULL) {
+		dev_err(&pdev->dev, "failed to request memory resource\n");
+		ret = -EBUSY;
+		goto err_free_clk;
+	}
+
+	pwm->mmio_base = ioremap(r->start, r->end - r->start + 1);
+	if (pwm->mmio_base == NULL) {
+		dev_err(&pdev->dev, "failed to ioremap() registers\n");
+		ret = -ENODEV;
+		goto err_free_mem;
+	}
+
+	__add_pwm(pwm);
+	platform_set_drvdata(pdev, pwm);
+	return pwm;
+
+err_free_mem:
+	release_mem_region(r->start, r->end - r->start + 1);
+err_free_clk:
+	clk_put(pwm->clk);
+err_free:
+	kfree(pwm);
+	return ERR_PTR(ret);
+}
+
+static int __devinit pxa25x_pwm_probe(struct platform_device *pdev)
+{
+	struct pwm_device *pwm = pwm_probe(pdev, pdev->id, NULL);
+
+	if (IS_ERR(pwm))
+		return PTR_ERR(pwm);
+
+	return 0;
+}
+
+static int __devinit pxa27x_pwm_probe(struct platform_device *pdev)
+{
+	struct pwm_device *pwm;
+
+	pwm = pwm_probe(pdev, pdev->id * 2, NULL);
+	if (IS_ERR(pwm))
+		return PTR_ERR(pwm);
+
+	pwm = pwm_probe(pdev, pdev->id * 2 + 1, pwm);
+	if (IS_ERR(pwm))
+		return PTR_ERR(pwm);
+
+	return 0;
+}
+
+static int __devexit pwm_remove(struct platform_device *pdev)
+{
+	struct pwm_device *pwm;
+	struct resource *r;
+
+	pwm = platform_get_drvdata(pdev);
+	if (pwm == NULL)
+		return -ENODEV;
+
+	mutex_lock(&pwm_lock);
+	list_del(&pwm->node);
+	mutex_unlock(&pwm_lock);
+
+	iounmap(pwm->mmio_base);
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	release_mem_region(r->start, r->end - r->start + 1);
+
+	clk_put(pwm->clk);
+	kfree(pwm);
+	return 0;
+}
+
+static struct platform_driver pxa25x_pwm_driver = {
+	.driver		= {
+		.name	= "pxa25x-pwm",
+	},
+	.probe		= pxa25x_pwm_probe,
+	.remove		= __devexit_p(pwm_remove),
+};
+
+static struct platform_driver pxa27x_pwm_driver = {
+	.driver		= {
+		.name	= "pxa27x-pwm",
+	},
+	.probe		= pxa27x_pwm_probe,
+	.remove		= __devexit_p(pwm_remove),
+};
+
+static int __init pwm_init(void)
+{
+	int ret = 0;
+
+	ret = platform_driver_register(&pxa25x_pwm_driver);
+	if (ret) {
+		printk(KERN_ERR "failed to register pxa25x_pwm_driver\n");
+		return ret;
+	}
+
+	ret = platform_driver_register(&pxa27x_pwm_driver);
+	if (ret) {
+		printk(KERN_ERR "failed to register pxa27x_pwm_driver\n");
+		return ret;
+	}
+
+	return ret;
+}
+arch_initcall(pwm_init);
+
+static void __exit pwm_exit(void)
+{
+	platform_driver_unregister(&pxa25x_pwm_driver);
+	platform_driver_unregister(&pxa27x_pwm_driver);
+}
+module_exit(pwm_exit);