158 lines
3.2 KiB
C
158 lines
3.2 KiB
C
/*
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* simple driver for PWM (Pulse Width Modulator) controller
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* 2008-02-13 initial version eric miao <eric.miao@marvell.com>
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* 2012 Robert Jarzmik <robert.jarzmik@free.fr>
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*/
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#include <common.h>
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#include <init.h>
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#include <errno.h>
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#include <io.h>
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#include <pwm.h>
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#include <mach/hardware.h>
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#include <mach/clock.h>
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#include <mach/pxa-regs.h>
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#include <mach/regs-pwm.h>
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#include <asm-generic/div64.h>
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#include <linux/compiler.h>
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/* PWM registers and bits definitions */
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#define PWMCR (0x00)
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#define PWMDCR (0x04)
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#define PWMPCR (0x08)
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#define PWMCR_SD (1 << 6)
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#define PWMDCR_FD (1 << 10)
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struct pxa_pwm_chip {
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struct pwm_chip chip;
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void __iomem *iobase;
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int id;
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int duty_ns;
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int period_ns;
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};
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static struct pxa_pwm_chip *to_pxa_pwm_chip(struct pwm_chip *chip)
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{
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return container_of(chip, struct pxa_pwm_chip, chip);
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}
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/*
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* period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
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* duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
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* PWM_CLK_RATE = 13 MHz
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*/
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static int pxa_pwm_config(struct pwm_chip *chip, int duty_ns, int period_ns)
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{
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unsigned long long c;
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unsigned long period_cycles, prescale, pv, dc;
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struct pxa_pwm_chip *pxa_pwm = to_pxa_pwm_chip(chip);
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c = pxa_get_pwmclk();
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c = c * period_ns;
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do_div(c, 1000000000);
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period_cycles = c;
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if (period_cycles < 1)
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period_cycles = 1;
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prescale = (period_cycles - 1) / 1024;
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pv = period_cycles / (prescale + 1) - 1;
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if (prescale > 63)
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return -EINVAL;
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if (duty_ns == period_ns)
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dc = PWMDCR_FD;
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else
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dc = (pv + 1) * duty_ns / period_ns;
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pxa_pwm->duty_ns = duty_ns;
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pxa_pwm->period_ns = period_ns;
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/* NOTE: the clock to PWM has to be enabled first
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* before writing to the registers
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*/
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__raw_writel(prescale, pxa_pwm->iobase + PWMCR);
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__raw_writel(dc, pxa_pwm->iobase + PWMDCR);
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__raw_writel(pv, pxa_pwm->iobase + PWMPCR);
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return 0;
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}
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static int pxa_pwm_enable(struct pwm_chip *chip)
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{
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struct pxa_pwm_chip *pxa_pwm = to_pxa_pwm_chip(chip);
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switch (pxa_pwm->id) {
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case 0:
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case 2:
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CKEN |= CKEN_PWM0;
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break;
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case 1:
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case 3:
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CKEN |= CKEN_PWM1;
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break;
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default:
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return -EINVAL;
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}
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return 0;
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}
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static void pxa_pwm_disable(struct pwm_chip *chip)
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{
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struct pxa_pwm_chip *pxa_pwm = to_pxa_pwm_chip(chip);
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switch (pxa_pwm->id) {
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case 0:
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case 2:
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CKEN &= ~CKEN_PWM0;
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break;
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case 1:
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case 3:
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CKEN &= ~CKEN_PWM1;
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break;
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default:
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break;
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}
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}
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static struct pwm_ops pxa_pwm_ops = {
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.config = pxa_pwm_config,
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.enable = pxa_pwm_enable,
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.disable = pxa_pwm_disable,
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};
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static int pxa_pwm_probe(struct device_d *dev)
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{
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struct pxa_pwm_chip *chip;
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chip = xzalloc(sizeof(*chip));
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chip->chip.devname = asprintf("pwm%d", dev->id);
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chip->chip.ops = &pxa_pwm_ops;
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chip->iobase = dev_request_mem_region(dev, 0);
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chip->id = dev->id;
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dev->priv = chip;
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return pwmchip_add(&chip->chip, dev);
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}
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static struct driver_d pxa_pwm_driver = {
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.name = "pxa_pwm",
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.probe = pxa_pwm_probe,
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};
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static int __init pxa_pwm_init_driver(void)
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{
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CKEN &= ~CKEN_PWM0 & ~CKEN_PWM1;
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platform_driver_register(&pxa_pwm_driver);
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return 0;
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}
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device_initcall(pxa_pwm_init_driver);
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