diff options
Diffstat (limited to 'arch/arm/plat-pxa/pwm.c')
| -rw-r--r-- | arch/arm/plat-pxa/pwm.c | 303 |
1 files changed, 303 insertions, 0 deletions
diff --git a/arch/arm/plat-pxa/pwm.c b/arch/arm/plat-pxa/pwm.c new file mode 100644 index 000000000000..a9eabdcfa163 --- /dev/null +++ b/arch/arm/plat-pxa/pwm.c @@ -0,0 +1,303 @@ +/* + * linux/arch/arm/mach-pxa/pwm.c + * + * 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. + * + * 2008-02-13 initial version + * eric miao <eric.miao@marvell.com> + */ + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/platform_device.h> +#include <linux/err.h> +#include <linux/clk.h> +#include <linux/io.h> +#include <linux/pwm.h> + +#include <asm/div64.h> + +#define HAS_SECONDARY_PWM 0x10 +#define PWM_ID_BASE(d) ((d) & 0xf) + +static const struct platform_device_id pwm_id_table[] = { + /* PWM has_secondary_pwm? */ + { "pxa25x-pwm", 0 }, + { "pxa27x-pwm", 0 | HAS_SECONDARY_PWM }, + { "pxa168-pwm", 1 }, + { "pxa910-pwm", 1 }, + { }, +}; +MODULE_DEVICE_TABLE(platform, pwm_id_table); + +/* PWM registers and bits definitions */ +#define PWMCR (0x00) +#define PWMDCR (0x04) +#define PWMPCR (0x08) + +#define PWMCR_SD (1 << 6) +#define PWMDCR_FD (1 << 10) + +struct pwm_device { + struct list_head node; + struct pwm_device *secondary; + struct platform_device *pdev; + + const char *label; + struct clk *clk; + int clk_enabled; + void __iomem *mmio_base; + + unsigned int use_count; + unsigned int pwm_id; +}; + +/* + * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE + * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE + */ +int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns) +{ + unsigned long long c; + unsigned long period_cycles, prescale, pv, dc; + + if (pwm == NULL || period_ns == 0 || duty_ns > period_ns) + return -EINVAL; + + c = clk_get_rate(pwm->clk); + c = c * period_ns; + do_div(c, 1000000000); + period_cycles = c; + + if (period_cycles < 1) + period_cycles = 1; + prescale = (period_cycles - 1) / 1024; + pv = period_cycles / (prescale + 1) - 1; + + if (prescale > 63) + return -EINVAL; + + if (duty_ns == period_ns) + dc = PWMDCR_FD; + else + dc = (pv + 1) * duty_ns / period_ns; + + /* NOTE: the clock to PWM has to be enabled first + * before writing to the registers + */ + clk_enable(pwm->clk); + __raw_writel(prescale, pwm->mmio_base + PWMCR); + __raw_writel(dc, pwm->mmio_base + PWMDCR); + __raw_writel(pv, pwm->mmio_base + PWMPCR); + clk_disable(pwm->clk); + + return 0; +} +EXPORT_SYMBOL(pwm_config); + +int pwm_enable(struct pwm_device *pwm) +{ + int rc = 0; + + if (!pwm->clk_enabled) { + rc = clk_enable(pwm->clk); + if (!rc) + pwm->clk_enabled = 1; + } + return rc; +} +EXPORT_SYMBOL(pwm_enable); + +void pwm_disable(struct pwm_device *pwm) +{ + if (pwm->clk_enabled) { + clk_disable(pwm->clk); + pwm->clk_enabled = 0; + } +} +EXPORT_SYMBOL(pwm_disable); + +static DEFINE_MUTEX(pwm_lock); +static LIST_HEAD(pwm_list); + +struct pwm_device *pwm_request(int pwm_id, const char *label) +{ + struct pwm_device *pwm; + int found = 0; + + mutex_lock(&pwm_lock); + + list_for_each_entry(pwm, &pwm_list, node) { + if (pwm->pwm_id == pwm_id) { + found = 1; + break; + } + } + + if (found) { + if (pwm->use_count == 0) { + pwm->use_count++; + pwm->label = label; + } else + pwm = ERR_PTR(-EBUSY); + } else + pwm = ERR_PTR(-ENOENT); + + mutex_unlock(&pwm_lock); + return pwm; +} +EXPORT_SYMBOL(pwm_request); + +void pwm_free(struct pwm_device *pwm) +{ + mutex_lock(&pwm_lock); + + if (pwm->use_count) { + pwm->use_count--; + pwm->label = NULL; + } else + pr_warning("PWM device already freed\n"); + + mutex_unlock(&pwm_lock); +} +EXPORT_SYMBOL(pwm_free); + +static inline void __add_pwm(struct pwm_device *pwm) +{ + mutex_lock(&pwm_lock); + list_add_tail(&pwm->node, &pwm_list); + mutex_unlock(&pwm_lock); +} + +static int __devinit pwm_probe(struct platform_device *pdev) +{ + struct platform_device_id *id = platform_get_device_id(pdev); + struct pwm_device *pwm, *secondary = NULL; + struct resource *r; + int ret = 0; + + pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL); + if (pwm == NULL) { + dev_err(&pdev->dev, "failed to allocate memory\n"); + return -ENOMEM; + } + + pwm->clk = clk_get(&pdev->dev, NULL); + if (IS_ERR(pwm->clk)) { + ret = PTR_ERR(pwm->clk); + goto err_free; + } + pwm->clk_enabled = 0; + + pwm->use_count = 0; + pwm->pwm_id = PWM_ID_BASE(id->driver_data) + pdev->id; + pwm->pdev = pdev; + + r = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (r == NULL) { + dev_err(&pdev->dev, "no memory resource defined\n"); + ret = -ENODEV; + goto err_free_clk; + } + + r = request_mem_region(r->start, r->end - r->start + 1, pdev->name); + if (r == NULL) { + dev_err(&pdev->dev, "failed to request memory resource\n"); + ret = -EBUSY; + goto err_free_clk; + } + + pwm->mmio_base = ioremap(r->start, r->end - r->start + 1); + if (pwm->mmio_base == NULL) { + dev_err(&pdev->dev, "failed to ioremap() registers\n"); + ret = -ENODEV; + goto err_free_mem; + } + + if (id->driver_data & HAS_SECONDARY_PWM) { + secondary = kzalloc(sizeof(struct pwm_device), GFP_KERNEL); + if (secondary == NULL) { + ret = -ENOMEM; + goto err_free_mem; + } + + *secondary = *pwm; + pwm->secondary = secondary; + + /* registers for the second PWM has offset of 0x10 */ + secondary->mmio_base = pwm->mmio_base + 0x10; + secondary->pwm_id = pdev->id + 2; + } + + __add_pwm(pwm); + if (secondary) + __add_pwm(secondary); + + platform_set_drvdata(pdev, pwm); + return 0; + +err_free_mem: + release_mem_region(r->start, r->end - r->start + 1); +err_free_clk: + clk_put(pwm->clk); +err_free: + kfree(pwm); + return ret; +} + +static int __devexit pwm_remove(struct platform_device *pdev) +{ + struct pwm_device *pwm; + struct resource *r; + + pwm = platform_get_drvdata(pdev); + if (pwm == NULL) + return -ENODEV; + + mutex_lock(&pwm_lock); + + if (pwm->secondary) { + list_del(&pwm->secondary->node); + kfree(pwm->secondary); + } + + list_del(&pwm->node); + mutex_unlock(&pwm_lock); + + iounmap(pwm->mmio_base); + + r = platform_get_resource(pdev, IORESOURCE_MEM, 0); + release_mem_region(r->start, r->end - r->start + 1); + + clk_put(pwm->clk); + kfree(pwm); + return 0; +} + +static struct platform_driver pwm_driver = { + .driver = { + .name = "pxa25x-pwm", + .owner = THIS_MODULE, + }, + .probe = pwm_probe, + .remove = __devexit_p(pwm_remove), + .id_table = pwm_id_table, +}; + +static int __init pwm_init(void) +{ + return platform_driver_register(&pwm_driver); +} +arch_initcall(pwm_init); + +static void __exit pwm_exit(void) +{ + platform_driver_unregister(&pwm_driver); +} +module_exit(pwm_exit); + +MODULE_LICENSE("GPL v2"); |