Messages in this thread Patch in this message | | | From | Sascha Hauer <> | Subject | [PATCH 2/2] pwm: Add a i.MX23/28 pwm driver | Date | Wed, 29 Jun 2011 11:03:35 +0200 |
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Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> --- drivers/pwm/Kconfig | 6 +- drivers/pwm/Makefile | 1 + drivers/pwm/mxs-pwm.c | 321 +++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 327 insertions(+), 1 deletions(-) create mode 100644 drivers/pwm/mxs-pwm.c
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig index 93c1052..5694574 100644 --- a/drivers/pwm/Kconfig +++ b/drivers/pwm/Kconfig @@ -2,11 +2,15 @@ menuconfig PWM bool "PWM Support" help This enables PWM support through the generic PWM framework. - You only need to enable this, if you also want to enable + You only need to enable this if you also want to enable one or more of the PWM drivers below. If unsure, say N. if PWM +config PWM_MXS + tristate "MXS pwm support" + depends on ARCH_MXS + endif diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile index 3469c3d..2cadd50 100644 --- a/drivers/pwm/Makefile +++ b/drivers/pwm/Makefile @@ -1 +1,2 @@ obj-$(CONFIG_PWM) += core.o +obj-$(CONFIG_PWM_MXS) += mxs-pwm.o diff --git a/drivers/pwm/mxs-pwm.c b/drivers/pwm/mxs-pwm.c new file mode 100644 index 0000000..6788f48 --- /dev/null +++ b/drivers/pwm/mxs-pwm.c @@ -0,0 +1,321 @@ +/* + * Copyright (C) 2011 Pengutronix + * Sascha Hauer <s.hauer@pengutronix.de> + * + * simple driver for PWM (Pulse Width Modulator) controller + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * Derived from pxa PWM driver by eric miao <eric.miao@marvell.com> + */ + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/platform_device.h> +#include <linux/slab.h> +#include <linux/err.h> +#include <linux/clk.h> +#include <linux/delay.h> +#include <linux/io.h> +#include <linux/pwm.h> +#include <mach/hardware.h> +#include <asm/div64.h> + +struct mxs_pwm_device { + struct device *dev; + + struct clk *clk; + + int enabled; + void __iomem *mmio_base; + + unsigned int pwm_id; + + u32 val_active; + u32 val_period; + int period_us; + struct pwm_chip chip; +}; + +/* common register space */ +#define REG_PWM_CTRL 0x0 +#define REG_PWM_CTRL_SET 0x4 +#define REG_PWM_CTRL_CLEAR 0x8 +#define PWM_SFTRST (1 << 31) +#define PWM_CLKGATE (1 << 30) +#define PWM_ENABLE(p) (1 << (p)) + +/* per pwm register space */ +#define REG_ACTIVE 0x0 +#define REG_PERIOD 0x10 + +#define PERIOD_PERIOD(p) ((p) & 0xffff) +#define PERIOD_ACTIVE_HIGH (3 << 16) +#define PERIOD_INACTIVE_LOW (2 << 18) +#define PERIOD_CDIV(div) (((div) & 0x7) << 20) + +static void pwm_update(struct mxs_pwm_device *pwm) +{ + writel(pwm->val_active, pwm->mmio_base + REG_ACTIVE); + writel(pwm->val_period, pwm->mmio_base + REG_PERIOD); +} + +#define to_mxs_pwm_device(chip) container_of(chip, struct mxs_pwm_device, chip) + +static int mxs_pwm_config(struct pwm_chip *chip, int duty_ns, int period_ns) +{ + struct mxs_pwm_device *pwm = to_mxs_pwm_device(chip); + int div = 0; + unsigned long rate; + unsigned long long c; + unsigned long period_cycles, duty_cycles; + + rate = clk_get_rate(pwm->clk); + + dev_dbg(pwm->dev, "config: duty_ns: %d, period_ns: %d (clkrate %ld)\n", + duty_ns, period_ns, rate); + + while (1) { + c = rate / (1 << div); + c = c * period_ns; + do_div(c, 1000000000); + if (c < 0x10000) + break; + div++; + + if (div > 8) + return -EINVAL; + } + + period_cycles = c; + duty_cycles = period_cycles * duty_ns / period_ns; + + dev_dbg(pwm->dev, "config period_cycles: %ld duty_cycles: %ld\n", + period_cycles, duty_cycles); + + pwm->val_active = period_cycles << 16 | duty_cycles; + pwm->val_period = PERIOD_PERIOD(period_cycles) | PERIOD_ACTIVE_HIGH | + PERIOD_INACTIVE_LOW | PERIOD_CDIV(div); + pwm->period_us = period_ns / 1000; + + pwm_update(pwm); + + return 0; +} + +static void __iomem *pwm_base_common; +static int num_instances; +static DEFINE_MUTEX(pwm_common_mutex); + +/* + * each pwm has a separate register space but all share a common + * enable register. + */ +static int mxs_pwm_common_get(struct platform_device *pdev) +{ + struct resource *r = platform_get_resource(pdev, IORESOURCE_MEM, 0); + resource_size_t start = r->start & ~0xfff; + int ret = 0; + + mutex_lock(&pwm_common_mutex); + + if (!num_instances) { + r = request_mem_region(start, 0x10, "mxs-pwm-common"); + if (!r) + goto err_request; + + pwm_base_common = ioremap(start, 0x10); + if (!pwm_base_common) { + ret = -ENOMEM; + goto err_ioremap; + } + } + + writel(PWM_SFTRST | PWM_CLKGATE, pwm_base_common + REG_PWM_CTRL_CLEAR); + + num_instances++; + + mutex_unlock(&pwm_common_mutex); + + return 0; + +err_ioremap: + release_mem_region(start, 0x10); +err_request: + mutex_unlock(&pwm_common_mutex); + return ret; +} + +static void mxs_pwm_common_put(struct platform_device *pdev) +{ + struct resource *r = platform_get_resource(pdev, IORESOURCE_MEM, 0); + resource_size_t start = r->start & ~0xfff; + + mutex_lock(&pwm_common_mutex); + + num_instances--; + + if (!num_instances) { + iounmap(pwm_base_common); + release_mem_region(start, 0x10); + + writel(PWM_CLKGATE, pwm_base_common + REG_PWM_CTRL_SET); + } + + mutex_unlock(&pwm_common_mutex); +} + +static void __pwm_enable(struct mxs_pwm_device *pwm, int enable) +{ + void __iomem *reg; + + if (enable) + reg = pwm_base_common + REG_PWM_CTRL_SET; + else + reg = pwm_base_common + REG_PWM_CTRL_CLEAR; + + writel(PWM_ENABLE(pwm->chip.pwm_id), reg); +} + +static int mxs_pwm_enable(struct pwm_chip *chip) +{ + struct mxs_pwm_device *pwm = to_mxs_pwm_device(chip); + int ret = 0; + + dev_dbg(pwm->dev, "enable\n"); + + if (!pwm->enabled) { + ret = clk_enable(pwm->clk); + if (!ret) { + pwm->enabled = 1; + __pwm_enable(pwm, 1); + pwm_update(pwm); + } + } + return ret; +} + +static void mxs_pwm_disable(struct pwm_chip *chip) +{ + struct mxs_pwm_device *pwm = to_mxs_pwm_device(chip); + + dev_dbg(pwm->dev, "disable\n"); + + if (pwm->enabled) { + /* + * We need a little delay here, it takes one period for + * the last pwm_config call to take effect. If we disable + * the pwm too early it just freezes the current output + * state. + */ + usleep_range(pwm->period_us, pwm->period_us * 2); + __pwm_enable(pwm, 0); + clk_disable(pwm->clk); + pwm->enabled = 0; + } +} + +static struct pwm_ops mxs_pwm_ops = { + .enable = mxs_pwm_enable, + .disable = mxs_pwm_disable, + .config = mxs_pwm_config, + .owner = THIS_MODULE, +}; + +static int __devinit mxs_pwm_probe(struct platform_device *pdev) +{ + struct mxs_pwm_device *pwm; + struct resource *r; + int ret = 0; + + pwm = devm_kzalloc(&pdev->dev, sizeof(struct mxs_pwm_device), GFP_KERNEL); + if (pwm == NULL) { + dev_err(&pdev->dev, "failed to allocate memory\n"); + return -ENOMEM; + } + + pwm->chip.ops = &mxs_pwm_ops; + pwm->chip.pwm_id = pdev->id; + + r = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (!r) + return -ENODEV; + + r = devm_request_mem_region(&pdev->dev, r->start, resource_size(r), + pdev->name); + if (!r) + return -EBUSY; + + pwm->mmio_base = devm_ioremap(&pdev->dev, r->start, resource_size(r)); + if (!pwm->mmio_base) { + dev_err(&pdev->dev, "failed to ioremap() registers\n"); + return -ENOMEM; + } + + pwm->clk = clk_get(&pdev->dev, NULL); + if (IS_ERR(pwm->clk)) { + ret = PTR_ERR(pwm->clk); + goto err_out; + } + + ret = mxs_pwm_common_get(pdev); + if (ret) + goto err_free_clk; + + ret = pwmchip_add(&pwm->chip); + if (ret) + goto err_remove_common; + + platform_set_drvdata(pdev, pwm); + return 0; + +err_remove_common: + mxs_pwm_common_put(pdev); +err_free_clk: + clk_put(pwm->clk); +err_out: + return ret; +} + +static int __devexit mxs_pwm_remove(struct platform_device *pdev) +{ + struct mxs_pwm_device *pwm; + int ret; + + pwm = platform_get_drvdata(pdev); + + ret = pwmchip_remove(&pwm->chip); + if (ret) + return ret; + + clk_put(pwm->clk); + + mxs_pwm_common_put(pdev); + + return 0; +} + +static struct platform_driver mxs_pwm_driver = { + .driver = { + .name = "mxs-pwm", + }, + .probe = mxs_pwm_probe, + .remove = __devexit_p(mxs_pwm_remove), +}; + +static int __init mxs_pwm_init(void) +{ + return platform_driver_register(&mxs_pwm_driver); +} +arch_initcall(mxs_pwm_init); + +static void __exit mxs_pwm_exit(void) +{ + platform_driver_unregister(&mxs_pwm_driver); +} +module_exit(mxs_pwm_exit); + +MODULE_LICENSE("GPL v2"); +MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>"); -- 1.7.5.3
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