1 files changed, 199 insertions, 0 deletions

diff --git a/drivers/pwm/pwm-imx1.c b/drivers/pwm/pwm-imx1.c
new file mode 100644
index 000000000000..f8b2c2e001a7
--- /dev/null
+++ b/drivers/pwm/pwm-imx1.c
@@ -0,0 +1,199 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * simple driver for PWM (Pulse Width Modulator) controller
+ *
+ * Derived from pxa PWM driver by eric miao <eric.miao@marvell.com>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/slab.h>
+
+#define MX1_PWMC                        0x00   /* PWM Control Register */
+#define MX1_PWMS                        0x04   /* PWM Sample Register */
+#define MX1_PWMP                        0x08   /* PWM Period Register */
+
+#define MX1_PWMC_EN                     BIT(4)
+
+struct pwm_imx1_chip {
+        struct clk *clk_ipg;
+        struct clk *clk_per;
+        void __iomem *mmio_base;
+        struct pwm_chip chip;
+};
+
+#define to_pwm_imx1_chip(chip)  container_of(chip, struct pwm_imx1_chip, chip)
+
+static int pwm_imx1_clk_prepare_enable(struct pwm_chip *chip)
+{
+        struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
+        int ret;
+
+        ret = clk_prepare_enable(imx->clk_ipg);
+        if (ret)
+                return ret;
+
+        ret = clk_prepare_enable(imx->clk_per);
+        if (ret) {
+                clk_disable_unprepare(imx->clk_ipg);
+                return ret;
+        }
+
+        return 0;
+}
+
+static void pwm_imx1_clk_disable_unprepare(struct pwm_chip *chip)
+{
+        struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
+
+        clk_disable_unprepare(imx->clk_per);
+        clk_disable_unprepare(imx->clk_ipg);
+}
+
+static int pwm_imx1_config(struct pwm_chip *chip,
+                           struct pwm_device *pwm, int duty_ns, int period_ns)
+{
+        struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
+        u32 max, p;
+
+        /*
+         * 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).
+         */
+        max = readl(imx->mmio_base + MX1_PWMP);
+        p = max * duty_ns / period_ns;
+
+        writel(max - p, imx->mmio_base + MX1_PWMS);
+
+        return 0;
+}
+
+static int pwm_imx1_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+        struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
+        u32 value;
+        int ret;
+
+        ret = pwm_imx1_clk_prepare_enable(chip);
+        if (ret < 0)
+                return ret;
+
+        value = readl(imx->mmio_base + MX1_PWMC);
+        value |= MX1_PWMC_EN;
+        writel(value, imx->mmio_base + MX1_PWMC);
+
+        return 0;
+}
+
+static void pwm_imx1_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+        struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
+        u32 value;
+
+        value = readl(imx->mmio_base + MX1_PWMC);
+        value &= ~MX1_PWMC_EN;
+        writel(value, imx->mmio_base + MX1_PWMC);
+
+        pwm_imx1_clk_disable_unprepare(chip);
+}
+
+static const struct pwm_ops pwm_imx1_ops = {
+        .enable = pwm_imx1_enable,
+        .disable = pwm_imx1_disable,
+        .config = pwm_imx1_config,
+        .owner = THIS_MODULE,
+};
+
+static const struct of_device_id pwm_imx1_dt_ids[] = {
+        { .compatible = "fsl,imx1-pwm", },
+        { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, pwm_imx1_dt_ids);
+
+static int pwm_imx1_probe(struct platform_device *pdev)
+{
+        struct pwm_imx1_chip *imx;
+        struct resource *r;
+
+        imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL);
+        if (!imx)
+                return -ENOMEM;
+
+        platform_set_drvdata(pdev, imx);
+
+        imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
+        if (IS_ERR(imx->clk_ipg)) {
+                dev_err(&pdev->dev, "getting ipg clock failed with %ld\n",
+                                PTR_ERR(imx->clk_ipg));
+                return PTR_ERR(imx->clk_ipg);
+        }
+
+        imx->clk_per = devm_clk_get(&pdev->dev, "per");
+        if (IS_ERR(imx->clk_per)) {
+                int ret = PTR_ERR(imx->clk_per);
+
+                if (ret != -EPROBE_DEFER)
+                        dev_err(&pdev->dev,
+                                "failed to get peripheral clock: %d\n",
+                                ret);
+
+                return ret;
+        }
+
+        imx->chip.ops = &pwm_imx1_ops;
+        imx->chip.dev = &pdev->dev;
+        imx->chip.base = -1;
+        imx->chip.npwm = 1;
+
+        r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        imx->mmio_base = devm_ioremap_resource(&pdev->dev, r);
+        if (IS_ERR(imx->mmio_base))
+                return PTR_ERR(imx->mmio_base);
+
+        return pwmchip_add(&imx->chip);
+}
+
+static int pwm_imx1_remove(struct platform_device *pdev)
+{
+        struct pwm_imx1_chip *imx = platform_get_drvdata(pdev);
+
+        pwm_imx1_clk_disable_unprepare(&imx->chip);
+
+        return pwmchip_remove(&imx->chip);
+}
+
+static struct platform_driver pwm_imx1_driver = {
+        .driver = {
+                .name = "pwm-imx1",
+                .of_match_table = pwm_imx1_dt_ids,
+        },
+        .probe = pwm_imx1_probe,
+        .remove = pwm_imx1_remove,
+};
+module_platform_driver(pwm_imx1_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");