[ARM] MXC: add pwm driver for i.MX SoCs

This driver has been tested on MX27/MX31. It should work on MX1/MX1
aswell, but the actual setting of the PWM is missing so far.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

arch/arm/plat-mxc/Kconfig

@@ -44,4 +44,10 @@ config MXC_IRQ_PRIOR
 	  requirements for timing.
 	  Say N here, unless you have a specialized requirement.
 
+config MXC_PWM
+	tristate "Enable PWM driver"
+	depends on ARCH_MXC
+	help
+	  Enable support for the i.MX PWM controller(s).
+
 endif

arch/arm/plat-mxc/Makefile

@@ -7,3 +7,4 @@ obj-y := irq.o clock.o gpio.o time.o devices.o
 
 obj-$(CONFIG_ARCH_MX1) += iomux-mx1-mx2.o dma-mx1-mx2.o
 obj-$(CONFIG_ARCH_MX2) += iomux-mx1-mx2.o dma-mx1-mx2.o
+obj-$(CONFIG_MXC_PWM)  += pwm.o

arch/arm/plat-mxc/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.
+ *
+ * Derived from pxa PWM driver by 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>
+
+#if defined CONFIG_ARCH_MX1 || defined CONFIG_ARCH_MX21
+#define PWM_VER_1
+
+#define PWMCR	0x00	/* PWM Control Register		*/
+#define PWMSR	0x04	/* PWM Sample Register		*/
+#define PWMPR	0x08	/* PWM Period Register		*/
+#define PWMCNR	0x0C	/* PWM Counter Register		*/
+
+#define PWMCR_HCTR		(1 << 18)		/* Halfword FIFO Data Swapping	*/
+#define PWMCR_BCTR		(1 << 17)		/* Byte FIFO Data Swapping	*/
+#define PWMCR_SWR		(1 << 16)		/* Software Reset		*/
+#define PWMCR_CLKSRC_PERCLK	(0 << 15)		/* PERCLK Clock Source		*/
+#define PWMCR_CLKSRC_CLK32	(1 << 15)		/* 32KHz Clock Source		*/
+#define PWMCR_PRESCALER(x)	(((x - 1) & 0x7F) << 8)	/* PRESCALER			*/
+#define PWMCR_IRQ		(1 << 7)		/* Interrupt Request		*/
+#define PWMCR_IRQEN		(1 << 6)		/* Interrupt Request Enable	*/
+#define PWMCR_FIFOAV		(1 << 5)		/* FIFO Available		*/
+#define PWMCR_EN		(1 << 4)		/* Enables/Disables the PWM	*/
+#define PWMCR_REPEAT(x)		(((x) & 0x03) << 2)	/* Sample Repeats		*/
+#define PWMCR_DIV(x)		(((x) & 0x03) << 0)	/* Clock divider 2/4/8/16	*/
+
+#define MAX_DIV			(128 * 16)
+#endif
+
+#if defined CONFIG_MACH_MX27 || defined CONFIG_ARCH_MX31
+#define PWM_VER_2
+
+#define PWMCR	0x00	/* PWM Control Register		*/
+#define PWMSR	0x04	/* PWM Status Register		*/
+#define PWMIR	0x08	/* PWM Interrupt Register	*/
+#define PWMSAR	0x0C	/* PWM Sample Register		*/
+#define PWMPR	0x10	/* PWM Period Register		*/
+#define PWMCNR	0x14	/* PWM Counter Register		*/
+
+#define PWMCR_EN		(1 << 0)		/* Enables/Disables the PWM	*/
+#define PWMCR_REPEAT(x)		(((x) & 0x03) << 1)	/* Sample Repeats		*/
+#define PWMCR_SWR		(1 << 3)		/* Software Reset		*/
+#define PWMCR_PRESCALER(x)	(((x - 1) & 0xFFF) << 4)/* PRESCALER			*/
+#define PWMCR_CLKSRC(x)		(((x) & 0x3) << 16)
+#define PWMCR_CLKSRC_OFF	(0 << 16)
+#define PWMCR_CLKSRC_IPG	(1 << 16)
+#define PWMCR_CLKSRC_IPG_HIGH	(2 << 16)
+#define PWMCR_CLKSRC_CLK32	(3 << 16)
+#define PWMCR_POUTC
+#define PWMCR_HCTR		(1 << 20)		/* Halfword FIFO Data Swapping	*/
+#define PWMCR_BCTR		(1 << 21)		/* Byte FIFO Data Swapping	*/
+#define PWMCR_DBGEN		(1 << 22)		/* Debug Mode			*/
+#define PWMCR_WAITEN		(1 << 23)		/* Wait Mode			*/
+#define PWMCR_DOZEN		(1 << 24)		/* Doze Mode			*/
+#define PWMCR_STOPEN		(1 << 25)		/* Stop Mode			*/
+#define PWMCR_FWM(x)		(((x) & 0x3) << 26)	/* FIFO Water Mark		*/
+
+#define MAX_DIV 4096
+#endif
+
+#define PWMS_SAMPLE(x)		((x) & 0xFFFF)		/* Contains a two-sample word	*/
+#define PWMP_PERIOD(x)		((x) & 0xFFFF)		/* Represents the PWM's period	*/
+#define PWMC_COUNTER(x)		((x) & 0xFFFF)		/* Represents the current count value	*/
+
+struct pwm_device {
+	struct list_head	node;
+	struct platform_device *pdev;
+
+	const char	*label;
+	struct clk	*clk;
+
+	int		clk_enabled;
+	void __iomem	*mmio_base;
+
+	unsigned int	use_count;
+	unsigned int	pwm_id;
+};
+
+int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
+{
+	unsigned long long c;
+	unsigned long period_cycles, duty_cycles, prescale;
+
+	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;
+
+	prescale = period_cycles / 0x10000 + 1;
+
+	period_cycles /= prescale;
+	c = (unsigned long long)period_cycles * duty_ns;
+	do_div(c, period_ns);
+	duty_cycles = c;
+
+#ifdef PWM_VER_2
+	writel(duty_cycles, pwm->mmio_base + PWMSAR);
+	writel(period_cycles, pwm->mmio_base + PWMPR);
+	writel(PWMCR_PRESCALER(prescale - 1) | PWMCR_CLKSRC_IPG_HIGH | PWMCR_EN,
+			pwm->mmio_base + PWMCR);
+#elif defined PWM_VER_1
+#error PWM not yet working on MX1 / MX21
+#endif
+
+	return 0;
+}
+EXPORT_SYMBOL(pwm_config);
+
+int pwm_enable(struct pwm_device *pwm)
+{
+	int rc = 0;
+
+	if (!pwm->clk_enabled) {
+		rc = clk_enable(pwm->clk);
+		if (!rc)
+			pwm->clk_enabled = 1;
+	}
+	return rc;
+}
+EXPORT_SYMBOL(pwm_enable);
+
+void pwm_disable(struct pwm_device *pwm)
+{
+	if (pwm->clk_enabled) {
+		clk_disable(pwm->clk);
+		pwm->clk_enabled = 0;
+	}
+}
+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) {
+			found = 1;
+			break;
+		}
+	}
+
+	if (found) {
+		if (pwm->use_count == 0) {
+			pwm->use_count++;
+			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
+		pr_warning("PWM device already freed\n");
+
+	mutex_unlock(&pwm_lock);
+}
+EXPORT_SYMBOL(pwm_free);
+
+static int __devinit mxc_pwm_probe(struct platform_device *pdev)
+{
+	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 -ENOMEM;
+	}
+
+	pwm->clk = clk_get(&pdev->dev, "pwm");
+
+	if (IS_ERR(pwm->clk)) {
+		ret = PTR_ERR(pwm->clk);
+		goto err_free;
+	}
+
+	pwm->clk_enabled = 0;
+
+	pwm->use_count = 0;
+	pwm->pwm_id = pdev->id;
+	pwm->pdev = pdev;
+
+	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;
+	}
+
+	mutex_lock(&pwm_lock);
+	list_add_tail(&pwm->node, &pwm_list);
+	mutex_unlock(&pwm_lock);
+
+	platform_set_drvdata(pdev, pwm);
+	return 0;
+
+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 ret;
+}
+
+static int __devexit mxc_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 mxc_pwm_driver = {
+	.driver		= {
+		.name	= "mxc_pwm",
+	},
+	.probe		= mxc_pwm_probe,
+	.remove		= __devexit_p(mxc_pwm_remove),
+};
+
+static int __init mxc_pwm_init(void)
+{
+	return platform_driver_register(&mxc_pwm_driver);
+}
+arch_initcall(mxc_pwm_init);
+
+static void __exit mxc_pwm_exit(void)
+{
+	platform_driver_unregister(&mxc_pwm_driver);
+}
+module_exit(mxc_pwm_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");
+