diff options
Diffstat (limited to 'drivers/pwm/pwm-stmpe.c')
| -rw-r--r-- | drivers/pwm/pwm-stmpe.c | 319 |
1 files changed, 319 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-stmpe.c b/drivers/pwm/pwm-stmpe.c new file mode 100644 index 000000000000..e464582a390a --- /dev/null +++ b/drivers/pwm/pwm-stmpe.c @@ -0,0 +1,319 @@ +/* + * Copyright (C) 2016 Linaro Ltd. + * + * Author: Linus Walleij <linus.walleij@linaro.org> + * + * 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. + * + */ + +#include <linux/bitops.h> +#include <linux/delay.h> +#include <linux/err.h> +#include <linux/mfd/stmpe.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/pwm.h> +#include <linux/slab.h> + +#define STMPE24XX_PWMCS 0x30 +#define PWMCS_EN_PWM0 BIT(0) +#define PWMCS_EN_PWM1 BIT(1) +#define PWMCS_EN_PWM2 BIT(2) +#define STMPE24XX_PWMIC0 0x38 +#define STMPE24XX_PWMIC1 0x39 +#define STMPE24XX_PWMIC2 0x3a + +#define STMPE_PWM_24XX_PINBASE 21 + +struct stmpe_pwm { + struct stmpe *stmpe; + struct pwm_chip chip; + u8 last_duty; +}; + +static inline struct stmpe_pwm *to_stmpe_pwm(struct pwm_chip *chip) +{ + return container_of(chip, struct stmpe_pwm, chip); +} + +static int stmpe_24xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct stmpe_pwm *stmpe_pwm = to_stmpe_pwm(chip); + u8 value; + int ret; + + ret = stmpe_reg_read(stmpe_pwm->stmpe, STMPE24XX_PWMCS); + if (ret < 0) { + dev_err(chip->dev, "error reading PWM#%u control\n", + pwm->hwpwm); + return ret; + } + + value = ret | BIT(pwm->hwpwm); + + ret = stmpe_reg_write(stmpe_pwm->stmpe, STMPE24XX_PWMCS, value); + if (ret) { + dev_err(chip->dev, "error writing PWM#%u control\n", + pwm->hwpwm); + return ret; + } + + return 0; +} + +static void stmpe_24xx_pwm_disable(struct pwm_chip *chip, + struct pwm_device *pwm) +{ + struct stmpe_pwm *stmpe_pwm = to_stmpe_pwm(chip); + u8 value; + int ret; + + ret = stmpe_reg_read(stmpe_pwm->stmpe, STMPE24XX_PWMCS); + if (ret < 0) { + dev_err(chip->dev, "error reading PWM#%u control\n", + pwm->hwpwm); + return; + } + + value = ret & ~BIT(pwm->hwpwm); + + ret = stmpe_reg_write(stmpe_pwm->stmpe, STMPE24XX_PWMCS, value); + if (ret) { + dev_err(chip->dev, "error writing PWM#%u control\n", + pwm->hwpwm); + return; + } +} + +/* STMPE 24xx PWM instructions */ +#define SMAX 0x007f +#define SMIN 0x00ff +#define GTS 0x0000 +#define LOAD BIT(14) /* Only available on 2403 */ +#define RAMPUP 0x0000 +#define RAMPDOWN BIT(7) +#define PRESCALE_512 BIT(14) +#define STEPTIME_1 BIT(8) +#define BRANCH (BIT(15) | BIT(13)) + +static int stmpe_24xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, + int duty_ns, int period_ns) +{ + struct stmpe_pwm *stmpe_pwm = to_stmpe_pwm(chip); + unsigned int i, pin; + u16 program[3] = { + SMAX, + GTS, + GTS, + }; + u8 offset; + int ret; + + /* Make sure we are disabled */ + if (pwm_is_enabled(pwm)) { + stmpe_24xx_pwm_disable(chip, pwm); + } else { + /* Connect the PWM to the pin */ + pin = pwm->hwpwm; + + /* On STMPE2401 and 2403 pins 21,22,23 are used */ + if (stmpe_pwm->stmpe->partnum == STMPE2401 || + stmpe_pwm->stmpe->partnum == STMPE2403) + pin += STMPE_PWM_24XX_PINBASE; + + ret = stmpe_set_altfunc(stmpe_pwm->stmpe, BIT(pin), + STMPE_BLOCK_PWM); + if (ret) { + dev_err(chip->dev, "unable to connect PWM#%u to pin\n", + pwm->hwpwm); + return ret; + } + } + + /* STMPE24XX */ + switch (pwm->hwpwm) { + case 0: + offset = STMPE24XX_PWMIC0; + break; + + case 1: + offset = STMPE24XX_PWMIC1; + break; + + case 2: + offset = STMPE24XX_PWMIC1; + break; + + default: + /* Should not happen as npwm is 3 */ + return -ENODEV; + } + + dev_dbg(chip->dev, "PWM#%u: config duty %d ns, period %d ns\n", + pwm->hwpwm, duty_ns, period_ns); + + if (duty_ns == 0) { + if (stmpe_pwm->stmpe->partnum == STMPE2401) + program[0] = SMAX; /* off all the time */ + + if (stmpe_pwm->stmpe->partnum == STMPE2403) + program[0] = LOAD | 0xff; /* LOAD 0xff */ + + stmpe_pwm->last_duty = 0x00; + } else if (duty_ns == period_ns) { + if (stmpe_pwm->stmpe->partnum == STMPE2401) + program[0] = SMIN; /* on all the time */ + + if (stmpe_pwm->stmpe->partnum == STMPE2403) + program[0] = LOAD | 0x00; /* LOAD 0x00 */ + + stmpe_pwm->last_duty = 0xff; + } else { + u8 value, last = stmpe_pwm->last_duty; + unsigned long duty; + + /* + * Counter goes from 0x00 to 0xff repeatedly at 32768 Hz, + * (means a period of 30517 ns) then this is compared to the + * counter from the ramp, if this is >= PWM counter the output + * is high. With LOAD we can define how much of the cycle it + * is on. + * + * Prescale = 0 -> 2 kHz -> T = 1/f = 488281.25 ns + */ + + /* Scale to 0..0xff */ + duty = duty_ns * 256; + duty = DIV_ROUND_CLOSEST(duty, period_ns); + value = duty; + + if (value == last) { + /* Run the old program */ + if (pwm_is_enabled(pwm)) + stmpe_24xx_pwm_enable(chip, pwm); + + return 0; + } else if (stmpe_pwm->stmpe->partnum == STMPE2403) { + /* STMPE2403 can simply set the right PWM value */ + program[0] = LOAD | value; + program[1] = 0x0000; + } else if (stmpe_pwm->stmpe->partnum == STMPE2401) { + /* STMPE2401 need a complex program */ + u16 incdec = 0x0000; + + if (last < value) + /* Count up */ + incdec = RAMPUP | (value - last); + else + /* Count down */ + incdec = RAMPDOWN | (last - value); + + /* Step to desired value, smoothly */ + program[0] = PRESCALE_512 | STEPTIME_1 | incdec; + + /* Loop eternally to 0x00 */ + program[1] = BRANCH; + } + + dev_dbg(chip->dev, + "PWM#%u: value = %02x, last_duty = %02x, program=%04x,%04x,%04x\n", + pwm->hwpwm, value, last, program[0], program[1], + program[2]); + stmpe_pwm->last_duty = value; + } + + /* + * We can write programs of up to 64 16-bit words into this channel. + */ + for (i = 0; i < ARRAY_SIZE(program); i++) { + u8 value; + + value = (program[i] >> 8) & 0xff; + + ret = stmpe_reg_write(stmpe_pwm->stmpe, offset, value); + if (ret) { + dev_err(chip->dev, "error writing register %02x: %d\n", + offset, ret); + return ret; + } + + value = program[i] & 0xff; + + ret = stmpe_reg_write(stmpe_pwm->stmpe, offset, value); + if (ret) { + dev_err(chip->dev, "error writing register %02x: %d\n", + offset, ret); + return ret; + } + } + + /* If we were enabled, re-enable this PWM */ + if (pwm_is_enabled(pwm)) + stmpe_24xx_pwm_enable(chip, pwm); + + /* Sleep for 200ms so we're sure it will take effect */ + msleep(200); + + dev_dbg(chip->dev, "programmed PWM#%u, %u bytes\n", pwm->hwpwm, i); + + return 0; +} + +static const struct pwm_ops stmpe_24xx_pwm_ops = { + .config = stmpe_24xx_pwm_config, + .enable = stmpe_24xx_pwm_enable, + .disable = stmpe_24xx_pwm_disable, + .owner = THIS_MODULE, +}; + +static int __init stmpe_pwm_probe(struct platform_device *pdev) +{ + struct stmpe *stmpe = dev_get_drvdata(pdev->dev.parent); + struct stmpe_pwm *pwm; + int ret; + + pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL); + if (!pwm) + return -ENOMEM; + + pwm->stmpe = stmpe; + pwm->chip.dev = &pdev->dev; + pwm->chip.base = -1; + + if (stmpe->partnum == STMPE2401 || stmpe->partnum == STMPE2403) { + pwm->chip.ops = &stmpe_24xx_pwm_ops; + pwm->chip.npwm = 3; + } else { + if (stmpe->partnum == STMPE1601) + dev_err(&pdev->dev, "STMPE1601 not yet supported\n"); + else + dev_err(&pdev->dev, "Unknown STMPE PWM\n"); + + return -ENODEV; + } + + ret = stmpe_enable(stmpe, STMPE_BLOCK_PWM); + if (ret) + return ret; + + ret = pwmchip_add(&pwm->chip); + if (ret) { + stmpe_disable(stmpe, STMPE_BLOCK_PWM); + return ret; + } + + platform_set_drvdata(pdev, pwm); + + return 0; +} + +static struct platform_driver stmpe_pwm_driver = { + .driver = { + .name = "stmpe-pwm", + }, +}; +builtin_platform_driver_probe(stmpe_pwm_driver, stmpe_pwm_probe); |