diff options
Diffstat (limited to 'drivers/pwm/pwm-vt8500.c')
| -rw-r--r-- | drivers/pwm/pwm-vt8500.c | 177 |
1 files changed, 177 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-vt8500.c b/drivers/pwm/pwm-vt8500.c new file mode 100644 index 00000000000..548021439f0 --- /dev/null +++ b/drivers/pwm/pwm-vt8500.c @@ -0,0 +1,177 @@ +/* + * drivers/pwm/pwm-vt8500.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 + +struct vt8500_chip { + struct pwm_chip chip; + void __iomem *base; +}; + +#define to_vt8500_chip(chip) container_of(chip, struct vt8500_chip, chip) + +#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); +} + +static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, + int duty_ns, int period_ns) +{ + struct vt8500_chip *vt8500 = to_vt8500_chip(chip); + unsigned long long c; + unsigned long period_cycles, prescale, pv, dc; + + 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(vt8500->base + 0x40 + pwm->hwpwm, (1 << 1)); + writel(prescale, vt8500->base + 0x4 + (pwm->hwpwm << 4)); + + pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 2)); + writel(pv, vt8500->base + 0x8 + (pwm->hwpwm << 4)); + + pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 3)); + writel(dc, vt8500->base + 0xc + (pwm->hwpwm << 4)); + + return 0; +} + +static int vt8500_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct vt8500_chip *vt8500 = to_vt8500_chip(chip); + + pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 0)); + writel(5, vt8500->base + (pwm->hwpwm << 4)); + return 0; +} + +static void vt8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct vt8500_chip *vt8500 = to_vt8500_chip(chip); + + pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 0)); + writel(0, vt8500->base + (pwm->hwpwm << 4)); +} + +static struct pwm_ops vt8500_pwm_ops = { + .enable = vt8500_pwm_enable, + .disable = vt8500_pwm_disable, + .config = vt8500_pwm_config, + .owner = THIS_MODULE, +}; + +static int __devinit pwm_probe(struct platform_device *pdev) +{ + struct vt8500_chip *chip; + struct resource *r; + int ret; + + chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL); + if (chip == NULL) { + dev_err(&pdev->dev, "failed to allocate memory\n"); + return -ENOMEM; + } + + chip->chip.dev = &pdev->dev; + chip->chip.ops = &vt8500_pwm_ops; + chip->chip.base = -1; + chip->chip.npwm = VT8500_NR_PWMS; + + r = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (r == NULL) { + dev_err(&pdev->dev, "no memory resource defined\n"); + return -ENODEV; + } + + chip->base = devm_request_and_ioremap(&pdev->dev, r); + if (chip->base == NULL) + return -EADDRNOTAVAIL; + + ret = pwmchip_add(&chip->chip); + if (ret < 0) + return ret; + + platform_set_drvdata(pdev, chip); + return ret; +} + +static int __devexit pwm_remove(struct platform_device *pdev) +{ + struct vt8500_chip *chip; + + chip = platform_get_drvdata(pdev); + if (chip == NULL) + return -ENODEV; + + return pwmchip_remove(&chip->chip); +} + +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"); |