--- /dev/null
+/*
+ * drivers/pwm/pwm-tegra.c
+ *
+ * Tegra pulse-width-modulation controller driver
+ *
+ * Copyright (c) 2010, NVIDIA Corporation.
+ * Based on arch/arm/plat-mxc/pwm.c by Sascha Hauer <s.hauer@pengutronix.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/pwm.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#define PWM_ENABLE (1 << 31)
+#define PWM_DUTY_WIDTH 8
+#define PWM_DUTY_SHIFT 16
+#define PWM_SCALE_WIDTH 13
+#define PWM_SCALE_SHIFT 0
+
+#define NUM_PWM 4
+
+struct tegra_pwm_chip {
+ struct pwm_chip chip;
+ struct device *dev;
+
+ struct clk *clk;
+
+ void __iomem *mmio_base;
+};
+
+static inline struct tegra_pwm_chip *to_tegra_pwm_chip(struct pwm_chip *chip)
+{
+ return container_of(chip, struct tegra_pwm_chip, chip);
+}
+
+static inline u32 pwm_readl(struct tegra_pwm_chip *chip, unsigned int num)
+{
+ return readl(chip->mmio_base + (num << 4));
+}
+
+static inline void pwm_writel(struct tegra_pwm_chip *chip, unsigned int num,
+ unsigned long val)
+{
+ writel(val, chip->mmio_base + (num << 4));
+}
+
+static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
+ int duty_ns, int period_ns)
+{
+ struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
+ unsigned long long c;
+ unsigned long rate, hz;
+ u32 val = 0;
+ int err;
+
+ /*
+ * Convert from duty_ns / period_ns to a fixed number of duty ticks
+ * per (1 << PWM_DUTY_WIDTH) cycles and make sure to round to the
+ * nearest integer during division.
+ */
+ c = duty_ns * ((1 << PWM_DUTY_WIDTH) - 1) + period_ns / 2;
+ do_div(c, period_ns);
+
+ val = (u32)c << PWM_DUTY_SHIFT;
+
+ /*
+ * Compute the prescaler value for which (1 << PWM_DUTY_WIDTH)
+ * cycles at the PWM clock rate will take period_ns nanoseconds.
+ */
+ rate = clk_get_rate(pc->clk) >> PWM_DUTY_WIDTH;
+ hz = NSEC_PER_SEC / period_ns;
+
+ rate = (rate + (hz / 2)) / hz;
+
+ /*
+ * Since the actual PWM divider is the register's frequency divider
+ * field minus 1, we need to decrement to get the correct value to
+ * write to the register.
+ */
+ if (rate > 0)
+ rate--;
+
+ /*
+ * Make sure that the rate will fit in the register's frequency
+ * divider field.
+ */
+ if (rate >> PWM_SCALE_WIDTH)
+ return -EINVAL;
+
+ val |= rate << PWM_SCALE_SHIFT;
+
+ /*
+ * If the PWM channel is disabled, make sure to turn on the clock
+ * before writing the register. Otherwise, keep it enabled.
+ */
+ if (!test_bit(PWMF_ENABLED, &pwm->flags)) {
+ err = clk_prepare_enable(pc->clk);
+ if (err < 0)
+ return err;
+ } else
+ val |= PWM_ENABLE;
+
+ pwm_writel(pc, pwm->hwpwm, val);
+
+ /*
+ * If the PWM is not enabled, turn the clock off again to save power.
+ */
+ if (!test_bit(PWMF_ENABLED, &pwm->flags))
+ clk_disable_unprepare(pc->clk);
+
+ return 0;
+}
+
+static int tegra_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
+ int rc = 0;
+ u32 val;
+
+ rc = clk_prepare_enable(pc->clk);
+ if (rc < 0)
+ return rc;
+
+ val = pwm_readl(pc, pwm->hwpwm);
+ val |= PWM_ENABLE;
+ pwm_writel(pc, pwm->hwpwm, val);
+
+ return 0;
+}
+
+static void tegra_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
+ u32 val;
+
+ val = pwm_readl(pc, pwm->hwpwm);
+ val &= ~PWM_ENABLE;
+ pwm_writel(pc, pwm->hwpwm, val);
+
+ clk_disable_unprepare(pc->clk);
+}
+
+static const struct pwm_ops tegra_pwm_ops = {
+ .config = tegra_pwm_config,
+ .enable = tegra_pwm_enable,
+ .disable = tegra_pwm_disable,
+ .owner = THIS_MODULE,
+};
+
+static int tegra_pwm_probe(struct platform_device *pdev)
+{
+ struct tegra_pwm_chip *pwm;
+ struct resource *r;
+ int ret;
+
+ pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
+ if (!pwm)
+ return -ENOMEM;
+
+ pwm->dev = &pdev->dev;
+
+ r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r);
+ if (IS_ERR(pwm->mmio_base))
+ return PTR_ERR(pwm->mmio_base);
+
+ platform_set_drvdata(pdev, pwm);
+
+ pwm->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(pwm->clk))
+ return PTR_ERR(pwm->clk);
+
+ pwm->chip.dev = &pdev->dev;
+ pwm->chip.ops = &tegra_pwm_ops;
+ pwm->chip.base = -1;
+ pwm->chip.npwm = NUM_PWM;
+
+ ret = pwmchip_add(&pwm->chip);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
+ return ret;
+ }
+
+ return 0;
+}
+
+static int tegra_pwm_remove(struct platform_device *pdev)
+{
+ struct tegra_pwm_chip *pc = platform_get_drvdata(pdev);
+ int i;
+
+ if (WARN_ON(!pc))
+ return -ENODEV;
+
+ for (i = 0; i < NUM_PWM; i++) {
+ struct pwm_device *pwm = &pc->chip.pwms[i];
+
+ if (!test_bit(PWMF_ENABLED, &pwm->flags))
+ if (clk_prepare_enable(pc->clk) < 0)
+ continue;
+
+ pwm_writel(pc, i, 0);
+
+ clk_disable_unprepare(pc->clk);
+ }
+
+ return pwmchip_remove(&pc->chip);
+}
+
+static const struct of_device_id tegra_pwm_of_match[] = {
+ { .compatible = "nvidia,tegra20-pwm" },
+ { .compatible = "nvidia,tegra30-pwm" },
+ { }
+};
+
+MODULE_DEVICE_TABLE(of, tegra_pwm_of_match);
+
+static struct platform_driver tegra_pwm_driver = {
+ .driver = {
+ .name = "tegra-pwm",
+ .of_match_table = tegra_pwm_of_match,
+ },
+ .probe = tegra_pwm_probe,
+ .remove = tegra_pwm_remove,
+};
+
+module_platform_driver(tegra_pwm_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("NVIDIA Corporation");
+MODULE_ALIAS("platform:tegra-pwm");
Code Review / kvmfornfv.git / blobdiff