diff options
Diffstat (limited to 'drivers/pwm/pwm-tegra.c')
| -rw-r--r-- | drivers/pwm/pwm-tegra.c | 254 |
1 files changed, 254 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-tegra.c b/drivers/pwm/pwm-tegra.c new file mode 100644 index 00000000000..0950142d191 --- /dev/null +++ b/drivers/pwm/pwm-tegra.c @@ -0,0 +1,254 @@ +/* + * 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 = 1000000000ul / 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) { + dev_err(&pdev->dev, "failed to allocate memory\n"); + return -ENOMEM; + } + + pwm->dev = &pdev->dev; + + r = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (!r) { + dev_err(&pdev->dev, "no memory resources defined\n"); + return -ENODEV; + } + + pwm->mmio_base = devm_request_and_ioremap(&pdev->dev, r); + if (!pwm->mmio_base) { + dev_err(&pdev->dev, "failed to ioremap() region\n"); + return -EADDRNOTAVAIL; + } + + platform_set_drvdata(pdev, pwm); + + pwm->clk = 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); + clk_put(pwm->clk); + return ret; + } + + return 0; +} + +static int __devexit 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); + } + + pwmchip_remove(&pc->chip); + clk_put(pc->clk); + + return 0; +} + +static struct platform_driver tegra_pwm_driver = { + .driver = { + .name = "tegra-pwm", + }, + .probe = tegra_pwm_probe, + .remove = __devexit_p(tegra_pwm_remove), +}; + +module_platform_driver(tegra_pwm_driver); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("NVIDIA Corporation"); +MODULE_ALIAS("platform:tegra-pwm"); |