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path: root/drivers/pwm/pwm-imx.c
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Diffstat (limited to 'drivers/pwm/pwm-imx.c')
-rw-r--r--drivers/pwm/pwm-imx.c267
1 files changed, 267 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c
new file mode 100644
index 000000000000..900d14562de8
--- /dev/null
+++ b/drivers/pwm/pwm-imx.c
@@ -0,0 +1,267 @@
+/*
+ * 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/slab.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/pwm.h>
+#include <mach/hardware.h>
+
+
+/* i.MX1 and i.MX21 share the same PWM function block: */
+
+#define MX1_PWMC 0x00 /* PWM Control Register */
+#define MX1_PWMS 0x04 /* PWM Sample Register */
+#define MX1_PWMP 0x08 /* PWM Period Register */
+
+
+/* i.MX27, i.MX31, i.MX35 share the same PWM function block: */
+
+#define MX3_PWMCR 0x00 /* PWM Control Register */
+#define MX3_PWMSAR 0x0C /* PWM Sample Register */
+#define MX3_PWMPR 0x10 /* PWM Period Register */
+#define MX3_PWMCR_PRESCALER(x) (((x - 1) & 0xFFF) << 4)
+#define MX3_PWMCR_DOZEEN (1 << 24)
+#define MX3_PWMCR_WAITEN (1 << 23)
+#define MX3_PWMCR_DBGEN (1 << 22)
+#define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16)
+#define MX3_PWMCR_CLKSRC_IPG (1 << 16)
+#define MX3_PWMCR_EN (1 << 0)
+
+struct imx_chip {
+ struct clk *clk;
+
+ int clk_enabled;
+ void __iomem *mmio_base;
+
+ struct pwm_chip chip;
+};
+
+#define to_imx_chip(chip) container_of(chip, struct imx_chip, chip)
+
+static int imx_pwm_config(struct pwm_chip *chip,
+ struct pwm_device *pwm, int duty_ns, int period_ns)
+{
+ struct imx_chip *imx = to_imx_chip(chip);
+
+ if (!(cpu_is_mx1() || cpu_is_mx21())) {
+ unsigned long long c;
+ unsigned long period_cycles, duty_cycles, prescale;
+ u32 cr;
+
+ c = clk_get_rate(imx->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;
+
+ /*
+ * according to imx pwm RM, the real period value should be
+ * PERIOD value in PWMPR plus 2.
+ */
+ if (period_cycles > 2)
+ period_cycles -= 2;
+ else
+ period_cycles = 0;
+
+ writel(duty_cycles, imx->mmio_base + MX3_PWMSAR);
+ writel(period_cycles, imx->mmio_base + MX3_PWMPR);
+
+ cr = MX3_PWMCR_PRESCALER(prescale) |
+ MX3_PWMCR_DOZEEN | MX3_PWMCR_WAITEN |
+ MX3_PWMCR_DBGEN | MX3_PWMCR_EN;
+
+ if (cpu_is_mx25())
+ cr |= MX3_PWMCR_CLKSRC_IPG;
+ else
+ cr |= MX3_PWMCR_CLKSRC_IPG_HIGH;
+
+ writel(cr, imx->mmio_base + MX3_PWMCR);
+ } else if (cpu_is_mx1() || cpu_is_mx21()) {
+ /* The PWM subsystem allows for exact frequencies. However,
+ * I cannot connect a scope on my device to the PWM line and
+ * thus cannot provide the program the PWM controller
+ * exactly. Instead, I'm relying on the fact that the
+ * Bootloader (u-boot or WinCE+haret) has programmed the PWM
+ * function group already. So I'll just modify the PWM sample
+ * register to follow the ratio of duty_ns vs. period_ns
+ * accordingly.
+ *
+ * This is good enough for programming the brightness of
+ * the LCD backlight.
+ *
+ * The real implementation would divide PERCLK[0] first by
+ * both the prescaler (/1 .. /128) and then by CLKSEL
+ * (/2 .. /16).
+ */
+ u32 max = readl(imx->mmio_base + MX1_PWMP);
+ u32 p = max * duty_ns / period_ns;
+ writel(max - p, imx->mmio_base + MX1_PWMS);
+ } else {
+ BUG();
+ }
+
+ return 0;
+}
+
+static int imx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct imx_chip *imx = to_imx_chip(chip);
+ int rc = 0;
+
+ if (!imx->clk_enabled) {
+ rc = clk_prepare_enable(imx->clk);
+ if (!rc)
+ imx->clk_enabled = 1;
+ }
+ return rc;
+}
+
+static void imx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct imx_chip *imx = to_imx_chip(chip);
+
+ writel(0, imx->mmio_base + MX3_PWMCR);
+
+ if (imx->clk_enabled) {
+ clk_disable_unprepare(imx->clk);
+ imx->clk_enabled = 0;
+ }
+}
+
+static struct pwm_ops imx_pwm_ops = {
+ .enable = imx_pwm_enable,
+ .disable = imx_pwm_disable,
+ .config = imx_pwm_config,
+ .owner = THIS_MODULE,
+};
+
+static int __devinit imx_pwm_probe(struct platform_device *pdev)
+{
+ struct imx_chip *imx;
+ struct resource *r;
+ int ret = 0;
+
+ imx = kzalloc(sizeof(*imx), GFP_KERNEL);
+ if (imx == NULL) {
+ dev_err(&pdev->dev, "failed to allocate memory\n");
+ return -ENOMEM;
+ }
+
+ imx->clk = clk_get(&pdev->dev, "pwm");
+
+ if (IS_ERR(imx->clk)) {
+ ret = PTR_ERR(imx->clk);
+ goto err_free;
+ }
+
+ imx->chip.ops = &imx_pwm_ops;
+ imx->chip.dev = &pdev->dev;
+ imx->chip.base = -1;
+ imx->chip.npwm = 1;
+
+ imx->clk_enabled = 0;
+
+ 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, resource_size(r), pdev->name);
+ if (r == NULL) {
+ dev_err(&pdev->dev, "failed to request memory resource\n");
+ ret = -EBUSY;
+ goto err_free_clk;
+ }
+
+ imx->mmio_base = ioremap(r->start, resource_size(r));
+ if (imx->mmio_base == NULL) {
+ dev_err(&pdev->dev, "failed to ioremap() registers\n");
+ ret = -ENODEV;
+ goto err_free_mem;
+ }
+
+ ret = pwmchip_add(&imx->chip);
+ if (ret < 0)
+ goto err_iounmap;
+
+ platform_set_drvdata(pdev, imx);
+ return 0;
+
+err_iounmap:
+ iounmap(imx->mmio_base);
+err_free_mem:
+ release_mem_region(r->start, resource_size(r));
+err_free_clk:
+ clk_put(imx->clk);
+err_free:
+ kfree(imx);
+ return ret;
+}
+
+static int __devexit imx_pwm_remove(struct platform_device *pdev)
+{
+ struct imx_chip *imx;
+ struct resource *r;
+ int ret;
+
+ imx = platform_get_drvdata(pdev);
+ if (imx == NULL)
+ return -ENODEV;
+
+ ret = pwmchip_remove(&imx->chip);
+ if (ret)
+ return ret;
+
+ iounmap(imx->mmio_base);
+
+ r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ release_mem_region(r->start, resource_size(r));
+
+ clk_put(imx->clk);
+
+ kfree(imx);
+ return 0;
+}
+
+static struct platform_driver imx_pwm_driver = {
+ .driver = {
+ .name = "mxc_pwm",
+ },
+ .probe = imx_pwm_probe,
+ .remove = __devexit_p(imx_pwm_remove),
+};
+
+static int __init imx_pwm_init(void)
+{
+ return platform_driver_register(&imx_pwm_driver);
+}
+arch_initcall(imx_pwm_init);
+
+static void __exit imx_pwm_exit(void)
+{
+ platform_driver_unregister(&imx_pwm_driver);
+}
+module_exit(imx_pwm_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");
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