[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);