/* * 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 * * 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 #include #include #include #include #include #include #include #include #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 struct tegra_pwm_chip { struct pwm_chip chip; struct device *dev; struct clk *clk; struct reset_control*rst; void __iomem *regs; }; 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->regs + (num << 4)); } static inline void pwm_writel(struct tegra_pwm_chip *chip, unsigned int num, unsigned long val) { writel(val, chip->regs + (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 = duty_ns; 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 *= (1 << PWM_DUTY_WIDTH); c += 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 (!pwm_is_enabled(pwm)) { 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 (!pwm_is_enabled(pwm)) 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->regs = devm_ioremap_resource(&pdev->dev, r); if (IS_ERR(pwm->regs)) return PTR_ERR(pwm->regs); platform_set_drvdata(pdev, pwm); pwm->clk = devm_clk_get(&pdev->dev, NULL); if (IS_ERR(pwm->clk)) return PTR_ERR(pwm->clk); pwm->rst = devm_reset_control_get(&pdev->dev, "pwm"); if (IS_ERR(pwm->rst)) { ret = PTR_ERR(pwm->rst); dev_err(&pdev->dev, "Reset control is not found: %d\n", ret); return ret; } reset_control_deassert(pwm->rst); pwm->chip.dev = &pdev->dev; pwm->chip.ops = &tegra_pwm_ops; pwm->chip.base = -1; pwm->chip.npwm = 4; ret = pwmchip_add(&pwm->chip); if (ret < 0) { dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret); reset_control_assert(pwm->rst); return ret; } return 0; } static int tegra_pwm_remove(struct platform_device *pdev) { struct tegra_pwm_chip *pc = platform_get_drvdata(pdev); unsigned int i; int err; if (WARN_ON(!pc)) return -ENODEV; err = clk_prepare_enable(pc->clk); if (err < 0) return err; for (i = 0; i < pc->chip.npwm; i++) { struct pwm_device *pwm = &pc->chip.pwms[i]; if (!pwm_is_enabled(pwm)) if (clk_prepare_enable(pc->clk) < 0) continue; pwm_writel(pc, i, 0); clk_disable_unprepare(pc->clk); } reset_control_assert(pc->rst); 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");