diff options
Diffstat (limited to 'arch/arm/mach-vt8500/pwm.c')
| -rw-r--r-- | arch/arm/mach-vt8500/pwm.c | 265 |
1 files changed, 265 insertions, 0 deletions
diff --git a/arch/arm/mach-vt8500/pwm.c b/arch/arm/mach-vt8500/pwm.c new file mode 100644 index 000000000000..8ad825e93592 --- /dev/null +++ b/arch/arm/mach-vt8500/pwm.c @@ -0,0 +1,265 @@ +/* + * arch/arm/mach-vt8500/pwm.c + * + * Copyright (C) 2010 Alexey Charkov <alchark@gmail.com> + * + * This software is licensed under the terms of the GNU General Public + * License version 2, as published by the Free Software Foundation, and + * may be copied, distributed, and modified under those terms. + * + * 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. + */ + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/platform_device.h> +#include <linux/slab.h> +#include <linux/err.h> +#include <linux/io.h> +#include <linux/pwm.h> +#include <linux/delay.h> + +#include <asm/div64.h> + +#define VT8500_NR_PWMS 4 + +static DEFINE_MUTEX(pwm_lock); +static LIST_HEAD(pwm_list); + +struct pwm_device { + struct list_head node; + struct platform_device *pdev; + + const char *label; + + void __iomem *regbase; + + unsigned int use_count; + unsigned int pwm_id; +}; + +#define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t) +static inline void pwm_busy_wait(void __iomem *reg, u8 bitmask) +{ + int loops = msecs_to_loops(10); + while ((readb(reg) & bitmask) && --loops) + cpu_relax(); + + if (unlikely(!loops)) + pr_warning("Waiting for status bits 0x%x to clear timed out\n", + bitmask); +} + +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 = 25000000/2; /* wild guess --- need to implement clocks */ + c = c * period_ns; + do_div(c, 1000000000); + period_cycles = c; + + if (period_cycles < 1) + period_cycles = 1; + prescale = (period_cycles - 1) / 4096; + pv = period_cycles / (prescale + 1) - 1; + if (pv > 4095) + pv = 4095; + + if (prescale > 1023) + return -EINVAL; + + c = (unsigned long long)pv * duty_ns; + do_div(c, period_ns); + dc = c; + + pwm_busy_wait(pwm->regbase + 0x40 + pwm->pwm_id, (1 << 1)); + writel(prescale, pwm->regbase + 0x4 + (pwm->pwm_id << 4)); + + pwm_busy_wait(pwm->regbase + 0x40 + pwm->pwm_id, (1 << 2)); + writel(pv, pwm->regbase + 0x8 + (pwm->pwm_id << 4)); + + pwm_busy_wait(pwm->regbase + 0x40 + pwm->pwm_id, (1 << 3)); + writel(dc, pwm->regbase + 0xc + (pwm->pwm_id << 4)); + + return 0; +} +EXPORT_SYMBOL(pwm_config); + +int pwm_enable(struct pwm_device *pwm) +{ + pwm_busy_wait(pwm->regbase + 0x40 + pwm->pwm_id, (1 << 0)); + writel(5, pwm->regbase + (pwm->pwm_id << 4)); + return 0; +} +EXPORT_SYMBOL(pwm_enable); + +void pwm_disable(struct pwm_device *pwm) +{ + pwm_busy_wait(pwm->regbase + 0x40 + pwm->pwm_id, (1 << 0)); + writel(0, pwm->regbase + (pwm->pwm_id << 4)); +} +EXPORT_SYMBOL(pwm_disable); + +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 pwm_device *pwms; + struct resource *r; + int ret = 0; + int i; + + pwms = kzalloc(sizeof(struct pwm_device) * VT8500_NR_PWMS, GFP_KERNEL); + if (pwms == NULL) { + dev_err(&pdev->dev, "failed to allocate memory\n"); + return -ENOMEM; + } + + for (i = 0; i < VT8500_NR_PWMS; i++) { + pwms[i].use_count = 0; + pwms[i].pwm_id = i; + pwms[i].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; + } + + r = request_mem_region(r->start, resource_size(r), pdev->name); + if (r == NULL) { + dev_err(&pdev->dev, "failed to request memory resource\n"); + ret = -EBUSY; + goto err_free; + } + + pwms[0].regbase = ioremap(r->start, resource_size(r)); + if (pwms[0].regbase == NULL) { + dev_err(&pdev->dev, "failed to ioremap() registers\n"); + ret = -ENODEV; + goto err_free_mem; + } + + for (i = 1; i < VT8500_NR_PWMS; i++) + pwms[i].regbase = pwms[0].regbase; + + for (i = 0; i < VT8500_NR_PWMS; i++) + __add_pwm(&pwms[i]); + + platform_set_drvdata(pdev, pwms); + return 0; + +err_free_mem: + release_mem_region(r->start, resource_size(r)); +err_free: + kfree(pwms); + return ret; +} + +static int __devexit pwm_remove(struct platform_device *pdev) +{ + struct pwm_device *pwms; + struct resource *r; + int i; + + pwms = platform_get_drvdata(pdev); + if (pwms == NULL) + return -ENODEV; + + mutex_lock(&pwm_lock); + + for (i = 0; i < VT8500_NR_PWMS; i++) + list_del(&pwms[i].node); + mutex_unlock(&pwm_lock); + + iounmap(pwms[0].regbase); + + r = platform_get_resource(pdev, IORESOURCE_MEM, 0); + release_mem_region(r->start, resource_size(r)); + + kfree(pwms); + return 0; +} + +static struct platform_driver pwm_driver = { + .driver = { + .name = "vt8500-pwm", + .owner = THIS_MODULE, + }, + .probe = pwm_probe, + .remove = __devexit_p(pwm_remove), +}; + +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"); |