diff options
Diffstat (limited to 'drivers/pwm/pwm-mxs.c')
| -rw-r--r-- | drivers/pwm/pwm-mxs.c | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-mxs.c b/drivers/pwm/pwm-mxs.c new file mode 100644 index 00000000000..9602708372b --- /dev/null +++ b/drivers/pwm/pwm-mxs.c @@ -0,0 +1,207 @@ +/* + * Copyright 2012 Freescale Semiconductor, Inc. + * + * The code contained herein is licensed under the GNU General Public + * License. You may obtain a copy of the GNU General Public License + * Version 2 or later at the following locations: + * + * http://www.opensource.org/licenses/gpl-license.html + * http://www.gnu.org/copyleft/gpl.html + */ + +#include <linux/clk.h> +#include <linux/err.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/of_address.h> +#include <linux/platform_device.h> +#include <linux/pwm.h> +#include <linux/slab.h> +#include <mach/common.h> + +#define SET 0x4 +#define CLR 0x8 +#define TOG 0xc + +#define PWM_CTRL 0x0 +#define PWM_ACTIVE0 0x10 +#define PWM_PERIOD0 0x20 +#define PERIOD_PERIOD(p) ((p) & 0xffff) +#define PERIOD_PERIOD_MAX 0x10000 +#define PERIOD_ACTIVE_HIGH (3 << 16) +#define PERIOD_INACTIVE_LOW (2 << 18) +#define PERIOD_CDIV(div) (((div) & 0x7) << 20) +#define PERIOD_CDIV_MAX 8 + +struct mxs_pwm_chip { + struct pwm_chip chip; + struct device *dev; + struct clk *clk; + void __iomem *base; +}; + +#define to_mxs_pwm_chip(_chip) container_of(_chip, struct mxs_pwm_chip, chip) + +static int mxs_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, + int duty_ns, int period_ns) +{ + struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip); + int ret, div = 0; + unsigned int period_cycles, duty_cycles; + unsigned long rate; + unsigned long long c; + + rate = clk_get_rate(mxs->clk); + while (1) { + c = rate / (1 << div); + c = c * period_ns; + do_div(c, 1000000000); + if (c < PERIOD_PERIOD_MAX) + break; + div++; + if (div > PERIOD_CDIV_MAX) + return -EINVAL; + } + + period_cycles = c; + c *= duty_ns; + do_div(c, period_ns); + duty_cycles = c; + + /* + * 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)) { + ret = clk_prepare_enable(mxs->clk); + if (ret) + return ret; + } + + writel(duty_cycles << 16, + mxs->base + PWM_ACTIVE0 + pwm->hwpwm * 0x20); + writel(PERIOD_PERIOD(period_cycles) | PERIOD_ACTIVE_HIGH | + PERIOD_INACTIVE_LOW | PERIOD_CDIV(div), + mxs->base + PWM_PERIOD0 + pwm->hwpwm * 0x20); + + /* + * If the PWM is not enabled, turn the clock off again to save power. + */ + if (!test_bit(PWMF_ENABLED, &pwm->flags)) + clk_disable_unprepare(mxs->clk); + + return 0; +} + +static int mxs_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip); + int ret; + + ret = clk_prepare_enable(mxs->clk); + if (ret) + return ret; + + writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + SET); + + return 0; +} + +static void mxs_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip); + + writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + CLR); + + clk_disable_unprepare(mxs->clk); +} + +static const struct pwm_ops mxs_pwm_ops = { + .config = mxs_pwm_config, + .enable = mxs_pwm_enable, + .disable = mxs_pwm_disable, + .owner = THIS_MODULE, +}; + +static int mxs_pwm_probe(struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + struct mxs_pwm_chip *mxs; + int ret; + + mxs = devm_kzalloc(&pdev->dev, sizeof(*mxs), GFP_KERNEL); + if (!mxs) + return -ENOMEM; + + mxs->base = of_iomap(np, 0); + if (!mxs->base) + return -EADDRNOTAVAIL; + + mxs->clk = clk_get(&pdev->dev, NULL); + if (IS_ERR(mxs->clk)) { + ret = PTR_ERR(mxs->clk); + goto iounmap; + } + + mxs->chip.dev = &pdev->dev; + mxs->chip.ops = &mxs_pwm_ops; + mxs->chip.base = -1; + ret = of_property_read_u32(np, "fsl,pwm-number", &mxs->chip.npwm); + if (ret < 0) { + dev_err(&pdev->dev, "failed to get pwm number: %d\n", ret); + goto clk_put; + } + + ret = pwmchip_add(&mxs->chip); + if (ret < 0) { + dev_err(&pdev->dev, "failed to add pwm chip %d\n", ret); + goto clk_put; + } + + mxs->dev = &pdev->dev; + platform_set_drvdata(pdev, mxs); + + mxs_reset_block(mxs->base); + + return 0; + +clk_put: + clk_put(mxs->clk); +iounmap: + iounmap(mxs->base); + return ret; +} + +static int __devexit mxs_pwm_remove(struct platform_device *pdev) +{ + struct mxs_pwm_chip *mxs = platform_get_drvdata(pdev); + + pwmchip_remove(&mxs->chip); + clk_put(mxs->clk); + iounmap(mxs->base); + + return 0; +} + +static struct of_device_id mxs_pwm_dt_ids[] = { + { .compatible = "fsl,mxs-pwm", }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, mxs_pwm_dt_ids); + +static struct platform_driver mxs_pwm_driver = { + .driver = { + .name = "mxs-pwm", + .of_match_table = of_match_ptr(mxs_pwm_dt_ids), + }, + .probe = mxs_pwm_probe, + .remove = __devexit_p(mxs_pwm_remove), +}; +module_platform_driver(mxs_pwm_driver); + +MODULE_ALIAS("platform:mxs-pwm"); +MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>"); +MODULE_DESCRIPTION("Freescale MXS PWM Driver"); +MODULE_LICENSE("GPL v2"); |