diff options
Diffstat (limited to 'drivers/pwm/pwm-renesas-tpu.c')
| -rw-r--r-- | drivers/pwm/pwm-renesas-tpu.c | 474 |
1 files changed, 474 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-renesas-tpu.c b/drivers/pwm/pwm-renesas-tpu.c new file mode 100644 index 000000000000..2600892782c1 --- /dev/null +++ b/drivers/pwm/pwm-renesas-tpu.c @@ -0,0 +1,474 @@ +/* + * R-Mobile TPU PWM driver + * + * Copyright (C) 2012 Renesas Solutions Corp. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License + * + * 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/clk.h> +#include <linux/err.h> +#include <linux/io.h> +#include <linux/init.h> +#include <linux/ioport.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/platform_data/pwm-renesas-tpu.h> +#include <linux/platform_device.h> +#include <linux/pm_runtime.h> +#include <linux/pwm.h> +#include <linux/slab.h> +#include <linux/spinlock.h> + +#define TPU_TSTR 0x00 /* Timer start register (shared) */ + +#define TPU_TCRn 0x00 /* Timer control register */ +#define TPU_TCR_CCLR_NONE (0 << 5) +#define TPU_TCR_CCLR_TGRA (1 << 5) +#define TPU_TCR_CCLR_TGRB (2 << 5) +#define TPU_TCR_CCLR_TGRC (5 << 5) +#define TPU_TCR_CCLR_TGRD (6 << 5) +#define TPU_TCR_CKEG_RISING (0 << 3) +#define TPU_TCR_CKEG_FALLING (1 << 3) +#define TPU_TCR_CKEG_BOTH (2 << 3) +#define TPU_TMDRn 0x04 /* Timer mode register */ +#define TPU_TMDR_BFWT (1 << 6) +#define TPU_TMDR_BFB (1 << 5) +#define TPU_TMDR_BFA (1 << 4) +#define TPU_TMDR_MD_NORMAL (0 << 0) +#define TPU_TMDR_MD_PWM (2 << 0) +#define TPU_TIORn 0x08 /* Timer I/O control register */ +#define TPU_TIOR_IOA_0 (0 << 0) +#define TPU_TIOR_IOA_0_CLR (1 << 0) +#define TPU_TIOR_IOA_0_SET (2 << 0) +#define TPU_TIOR_IOA_0_TOGGLE (3 << 0) +#define TPU_TIOR_IOA_1 (4 << 0) +#define TPU_TIOR_IOA_1_CLR (5 << 0) +#define TPU_TIOR_IOA_1_SET (6 << 0) +#define TPU_TIOR_IOA_1_TOGGLE (7 << 0) +#define TPU_TIERn 0x0c /* Timer interrupt enable register */ +#define TPU_TSRn 0x10 /* Timer status register */ +#define TPU_TCNTn 0x14 /* Timer counter */ +#define TPU_TGRAn 0x18 /* Timer general register A */ +#define TPU_TGRBn 0x1c /* Timer general register B */ +#define TPU_TGRCn 0x20 /* Timer general register C */ +#define TPU_TGRDn 0x24 /* Timer general register D */ + +#define TPU_CHANNEL_OFFSET 0x10 +#define TPU_CHANNEL_SIZE 0x40 + +enum tpu_pin_state { + TPU_PIN_INACTIVE, /* Pin is driven inactive */ + TPU_PIN_PWM, /* Pin is driven by PWM */ + TPU_PIN_ACTIVE, /* Pin is driven active */ +}; + +struct tpu_device; + +struct tpu_pwm_device { + bool timer_on; /* Whether the timer is running */ + + struct tpu_device *tpu; + unsigned int channel; /* Channel number in the TPU */ + + enum pwm_polarity polarity; + unsigned int prescaler; + u16 period; + u16 duty; +}; + +struct tpu_device { + struct platform_device *pdev; + struct tpu_pwm_platform_data *pdata; + struct pwm_chip chip; + spinlock_t lock; + + void __iomem *base; + struct clk *clk; +}; + +#define to_tpu_device(c) container_of(c, struct tpu_device, chip) + +static void tpu_pwm_write(struct tpu_pwm_device *pwm, int reg_nr, u16 value) +{ + void __iomem *base = pwm->tpu->base + TPU_CHANNEL_OFFSET + + pwm->channel * TPU_CHANNEL_SIZE; + + iowrite16(value, base + reg_nr); +} + +static void tpu_pwm_set_pin(struct tpu_pwm_device *pwm, + enum tpu_pin_state state) +{ + static const char * const states[] = { "inactive", "PWM", "active" }; + + dev_dbg(&pwm->tpu->pdev->dev, "%u: configuring pin as %s\n", + pwm->channel, states[state]); + + switch (state) { + case TPU_PIN_INACTIVE: + tpu_pwm_write(pwm, TPU_TIORn, + pwm->polarity == PWM_POLARITY_INVERSED ? + TPU_TIOR_IOA_1 : TPU_TIOR_IOA_0); + break; + case TPU_PIN_PWM: + tpu_pwm_write(pwm, TPU_TIORn, + pwm->polarity == PWM_POLARITY_INVERSED ? + TPU_TIOR_IOA_0_SET : TPU_TIOR_IOA_1_CLR); + break; + case TPU_PIN_ACTIVE: + tpu_pwm_write(pwm, TPU_TIORn, + pwm->polarity == PWM_POLARITY_INVERSED ? + TPU_TIOR_IOA_0 : TPU_TIOR_IOA_1); + break; + } +} + +static void tpu_pwm_start_stop(struct tpu_pwm_device *pwm, int start) +{ + unsigned long flags; + u16 value; + + spin_lock_irqsave(&pwm->tpu->lock, flags); + value = ioread16(pwm->tpu->base + TPU_TSTR); + + if (start) + value |= 1 << pwm->channel; + else + value &= ~(1 << pwm->channel); + + iowrite16(value, pwm->tpu->base + TPU_TSTR); + spin_unlock_irqrestore(&pwm->tpu->lock, flags); +} + +static int tpu_pwm_timer_start(struct tpu_pwm_device *pwm) +{ + int ret; + + if (!pwm->timer_on) { + /* Wake up device and enable clock. */ + pm_runtime_get_sync(&pwm->tpu->pdev->dev); + ret = clk_prepare_enable(pwm->tpu->clk); + if (ret) { + dev_err(&pwm->tpu->pdev->dev, "cannot enable clock\n"); + return ret; + } + pwm->timer_on = true; + } + + /* + * Make sure the channel is stopped, as we need to reconfigure it + * completely. First drive the pin to the inactive state to avoid + * glitches. + */ + tpu_pwm_set_pin(pwm, TPU_PIN_INACTIVE); + tpu_pwm_start_stop(pwm, false); + + /* + * - Clear TCNT on TGRB match + * - Count on rising edge + * - Set prescaler + * - Output 0 until TGRA, output 1 until TGRB (active low polarity) + * - Output 1 until TGRA, output 0 until TGRB (active high polarity + * - PWM mode + */ + tpu_pwm_write(pwm, TPU_TCRn, TPU_TCR_CCLR_TGRB | TPU_TCR_CKEG_RISING | + pwm->prescaler); + tpu_pwm_write(pwm, TPU_TMDRn, TPU_TMDR_MD_PWM); + tpu_pwm_set_pin(pwm, TPU_PIN_PWM); + tpu_pwm_write(pwm, TPU_TGRAn, pwm->duty); + tpu_pwm_write(pwm, TPU_TGRBn, pwm->period); + + dev_dbg(&pwm->tpu->pdev->dev, "%u: TGRA 0x%04x TGRB 0x%04x\n", + pwm->channel, pwm->duty, pwm->period); + + /* Start the channel. */ + tpu_pwm_start_stop(pwm, true); + + return 0; +} + +static void tpu_pwm_timer_stop(struct tpu_pwm_device *pwm) +{ + if (!pwm->timer_on) + return; + + /* Disable channel. */ + tpu_pwm_start_stop(pwm, false); + + /* Stop clock and mark device as idle. */ + clk_disable_unprepare(pwm->tpu->clk); + pm_runtime_put(&pwm->tpu->pdev->dev); + + pwm->timer_on = false; +} + +/* ----------------------------------------------------------------------------- + * PWM API + */ + +static int tpu_pwm_request(struct pwm_chip *chip, struct pwm_device *_pwm) +{ + struct tpu_device *tpu = to_tpu_device(chip); + struct tpu_pwm_device *pwm; + + if (_pwm->hwpwm >= TPU_CHANNEL_MAX) + return -EINVAL; + + pwm = kzalloc(sizeof(*pwm), GFP_KERNEL); + if (pwm == NULL) + return -ENOMEM; + + pwm->tpu = tpu; + pwm->channel = _pwm->hwpwm; + pwm->polarity = tpu->pdata ? tpu->pdata->channels[pwm->channel].polarity + : PWM_POLARITY_NORMAL; + pwm->prescaler = 0; + pwm->period = 0; + pwm->duty = 0; + + pwm->timer_on = false; + + pwm_set_chip_data(_pwm, pwm); + + return 0; +} + +static void tpu_pwm_free(struct pwm_chip *chip, struct pwm_device *_pwm) +{ + struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm); + + tpu_pwm_timer_stop(pwm); + kfree(pwm); +} + +static int tpu_pwm_config(struct pwm_chip *chip, struct pwm_device *_pwm, + int duty_ns, int period_ns) +{ + static const unsigned int prescalers[] = { 1, 4, 16, 64 }; + struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm); + struct tpu_device *tpu = to_tpu_device(chip); + unsigned int prescaler; + bool duty_only = false; + u32 clk_rate; + u32 period; + u32 duty; + int ret; + + /* + * Pick a prescaler to avoid overflowing the counter. + * TODO: Pick the highest acceptable prescaler. + */ + clk_rate = clk_get_rate(tpu->clk); + + for (prescaler = 0; prescaler < ARRAY_SIZE(prescalers); ++prescaler) { + period = clk_rate / prescalers[prescaler] + / (NSEC_PER_SEC / period_ns); + if (period <= 0xffff) + break; + } + + if (prescaler == ARRAY_SIZE(prescalers) || period == 0) { + dev_err(&tpu->pdev->dev, "clock rate mismatch\n"); + return -ENOTSUPP; + } + + if (duty_ns) { + duty = clk_rate / prescalers[prescaler] + / (NSEC_PER_SEC / duty_ns); + if (duty > period) + return -EINVAL; + } else { + duty = 0; + } + + dev_dbg(&tpu->pdev->dev, + "rate %u, prescaler %u, period %u, duty %u\n", + clk_rate, prescalers[prescaler], period, duty); + + if (pwm->prescaler == prescaler && pwm->period == period) + duty_only = true; + + pwm->prescaler = prescaler; + pwm->period = period; + pwm->duty = duty; + + /* If the channel is disabled we're done. */ + if (!test_bit(PWMF_ENABLED, &_pwm->flags)) + return 0; + + if (duty_only && pwm->timer_on) { + /* + * If only the duty cycle changed and the timer is already + * running, there's no need to reconfigure it completely, Just + * modify the duty cycle. + */ + tpu_pwm_write(pwm, TPU_TGRAn, pwm->duty); + dev_dbg(&tpu->pdev->dev, "%u: TGRA 0x%04x\n", pwm->channel, + pwm->duty); + } else { + /* Otherwise perform a full reconfiguration. */ + ret = tpu_pwm_timer_start(pwm); + if (ret < 0) + return ret; + } + + if (duty == 0 || duty == period) { + /* + * To avoid running the timer when not strictly required, handle + * 0% and 100% duty cycles as fixed levels and stop the timer. + */ + tpu_pwm_set_pin(pwm, duty ? TPU_PIN_ACTIVE : TPU_PIN_INACTIVE); + tpu_pwm_timer_stop(pwm); + } + + return 0; +} + +static int tpu_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *_pwm, + enum pwm_polarity polarity) +{ + struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm); + + pwm->polarity = polarity; + + return 0; +} + +static int tpu_pwm_enable(struct pwm_chip *chip, struct pwm_device *_pwm) +{ + struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm); + int ret; + + ret = tpu_pwm_timer_start(pwm); + if (ret < 0) + return ret; + + /* + * To avoid running the timer when not strictly required, handle 0% and + * 100% duty cycles as fixed levels and stop the timer. + */ + if (pwm->duty == 0 || pwm->duty == pwm->period) { + tpu_pwm_set_pin(pwm, pwm->duty ? + TPU_PIN_ACTIVE : TPU_PIN_INACTIVE); + tpu_pwm_timer_stop(pwm); + } + + return 0; +} + +static void tpu_pwm_disable(struct pwm_chip *chip, struct pwm_device *_pwm) +{ + struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm); + + /* The timer must be running to modify the pin output configuration. */ + tpu_pwm_timer_start(pwm); + tpu_pwm_set_pin(pwm, TPU_PIN_INACTIVE); + tpu_pwm_timer_stop(pwm); +} + +static const struct pwm_ops tpu_pwm_ops = { + .request = tpu_pwm_request, + .free = tpu_pwm_free, + .config = tpu_pwm_config, + .set_polarity = tpu_pwm_set_polarity, + .enable = tpu_pwm_enable, + .disable = tpu_pwm_disable, + .owner = THIS_MODULE, +}; + +/* ----------------------------------------------------------------------------- + * Probe and remove + */ + +static int tpu_probe(struct platform_device *pdev) +{ + struct tpu_device *tpu; + struct resource *res; + int ret; + + tpu = devm_kzalloc(&pdev->dev, sizeof(*tpu), GFP_KERNEL); + if (tpu == NULL) { + dev_err(&pdev->dev, "failed to allocate driver data\n"); + return -ENOMEM; + } + + tpu->pdata = pdev->dev.platform_data; + + /* Map memory, get clock and pin control. */ + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (!res) { + dev_err(&pdev->dev, "failed to get I/O memory\n"); + return -ENXIO; + } + + tpu->base = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(tpu->base)) + return PTR_ERR(tpu->base); + + tpu->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(tpu->clk)) { + dev_err(&pdev->dev, "cannot get clock\n"); + return PTR_ERR(tpu->clk); + } + + /* Initialize and register the device. */ + platform_set_drvdata(pdev, tpu); + + spin_lock_init(&tpu->lock); + tpu->pdev = pdev; + + tpu->chip.dev = &pdev->dev; + tpu->chip.ops = &tpu_pwm_ops; + tpu->chip.base = -1; + tpu->chip.npwm = TPU_CHANNEL_MAX; + + ret = pwmchip_add(&tpu->chip); + if (ret < 0) { + dev_err(&pdev->dev, "failed to register PWM chip\n"); + return ret; + } + + dev_info(&pdev->dev, "TPU PWM %d registered\n", tpu->pdev->id); + + pm_runtime_enable(&pdev->dev); + + return 0; +} + +static int tpu_remove(struct platform_device *pdev) +{ + struct tpu_device *tpu = platform_get_drvdata(pdev); + int ret; + + ret = pwmchip_remove(&tpu->chip); + if (ret) + return ret; + + pm_runtime_disable(&pdev->dev); + + return 0; +} + +static struct platform_driver tpu_driver = { + .probe = tpu_probe, + .remove = tpu_remove, + .driver = { + .name = "renesas-tpu-pwm", + .owner = THIS_MODULE, + } +}; + +module_platform_driver(tpu_driver); + +MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>"); +MODULE_DESCRIPTION("Renesas TPU PWM Driver"); +MODULE_LICENSE("GPL v2"); +MODULE_ALIAS("platform:renesas-tpu-pwm"); |