diff options
Diffstat (limited to 'drivers/pwm/pxa_pwm.c')
| -rw-r--r-- | drivers/pwm/pxa_pwm.c | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/drivers/pwm/pxa_pwm.c b/drivers/pwm/pxa_pwm.c new file mode 100644 index 0000000000..cf1f96a10a --- /dev/null +++ b/drivers/pwm/pxa_pwm.c @@ -0,0 +1,157 @@ +/* + * 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> + * 2012 Robert Jarzmik <robert.jarzmik@free.fr> + */ + +#include <common.h> +#include <init.h> +#include <errno.h> +#include <io.h> +#include <pwm.h> + +#include <mach/hardware.h> +#include <mach/clock.h> +#include <mach/pxa-regs.h> +#include <mach/regs-pwm.h> +#include <asm-generic/div64.h> +#include <linux/compiler.h> + +/* 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 pxa_pwm_chip { + struct pwm_chip chip; + void __iomem *iobase; + int id; + int duty_ns; + int period_ns; +}; + +static struct pxa_pwm_chip *to_pxa_pwm_chip(struct pwm_chip *chip) +{ + return container_of(chip, struct pxa_pwm_chip, chip); +} + +/* + * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE + * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE + * PWM_CLK_RATE = 13 MHz + */ +static int pxa_pwm_config(struct pwm_chip *chip, int duty_ns, int period_ns) +{ + unsigned long long c; + unsigned long period_cycles, prescale, pv, dc; + struct pxa_pwm_chip *pxa_pwm = to_pxa_pwm_chip(chip); + + c = pxa_get_pwmclk(); + 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; + + pxa_pwm->duty_ns = duty_ns; + pxa_pwm->period_ns = period_ns; + + /* NOTE: the clock to PWM has to be enabled first + * before writing to the registers + */ + __raw_writel(prescale, pxa_pwm->iobase + PWMCR); + __raw_writel(dc, pxa_pwm->iobase + PWMDCR); + __raw_writel(pv, pxa_pwm->iobase + PWMPCR); + + return 0; +} + +static int pxa_pwm_enable(struct pwm_chip *chip) +{ + struct pxa_pwm_chip *pxa_pwm = to_pxa_pwm_chip(chip); + + switch (pxa_pwm->id) { + case 0: + case 2: + CKEN |= CKEN_PWM0; + break; + case 1: + case 3: + CKEN |= CKEN_PWM1; + break; + default: + return -EINVAL; + } + return 0; +} + +static void pxa_pwm_disable(struct pwm_chip *chip) +{ + struct pxa_pwm_chip *pxa_pwm = to_pxa_pwm_chip(chip); + + switch (pxa_pwm->id) { + case 0: + case 2: + CKEN &= ~CKEN_PWM0; + break; + case 1: + case 3: + CKEN &= ~CKEN_PWM1; + break; + default: + break; + } +} + +static struct pwm_ops pxa_pwm_ops = { + .config = pxa_pwm_config, + .enable = pxa_pwm_enable, + .disable = pxa_pwm_disable, +}; + +static int pxa_pwm_probe(struct device_d *dev) +{ + struct pxa_pwm_chip *chip; + + chip = xzalloc(sizeof(*chip)); + chip->chip.devname = asprintf("%s", dev_name(dev)); + chip->chip.ops = &pxa_pwm_ops; + chip->iobase = dev_request_mem_region(dev, 0); + chip->id = dev->id; + dev->priv = chip; + + return pwmchip_add(&chip->chip, dev); +} + +static struct driver_d pxa_pwm_driver = { + .name = "pxa_pwm", + .probe = pxa_pwm_probe, +}; + +static int __init pxa_pwm_init_driver(void) +{ + CKEN &= ~CKEN_PWM0 & ~CKEN_PWM1; + register_driver(&pxa_pwm_driver); + return 0; +} + +device_initcall(pxa_pwm_init_driver); |