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![Nobuhiro Iwamatsu](/assets/img/avatar_default.png)
Add driver for the PWM controller on Toshiba Visconti ARM SoC. Signed-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp> Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> [thierry.reding@gmail.com: fix up a couple of checkpatch warnings] Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
190 lines
5 KiB
C
190 lines
5 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Toshiba Visconti pulse-width-modulation controller driver
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*
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* Copyright (c) 2020 - 2021 TOSHIBA CORPORATION
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* Copyright (c) 2020 - 2021 Toshiba Electronic Devices & Storage Corporation
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*
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* Authors: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
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*
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* Limitations:
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* - The fixed input clock is running at 1 MHz and is divided by either 1,
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* 2, 4 or 8.
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* - When the settings of the PWM are modified, the new values are shadowed
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* in hardware until the PIPGM_PCSR register is written and the currently
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* running period is completed. This way the hardware switches atomically
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* from the old setting to the new.
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* - Disabling the hardware completes the currently running period and keeps
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* the output at low level at all times.
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*/
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#include <linux/err.h>
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#include <linux/io.h>
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#include <linux/module.h>
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#include <linux/of_device.h>
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#include <linux/platform_device.h>
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#include <linux/pwm.h>
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#define PIPGM_PCSR(ch) (0x400 + 4 * (ch))
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#define PIPGM_PDUT(ch) (0x420 + 4 * (ch))
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#define PIPGM_PWMC(ch) (0x440 + 4 * (ch))
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#define PIPGM_PWMC_PWMACT BIT(5)
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#define PIPGM_PWMC_CLK_MASK GENMASK(1, 0)
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#define PIPGM_PWMC_POLARITY_MASK GENMASK(5, 5)
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struct visconti_pwm_chip {
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struct pwm_chip chip;
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void __iomem *base;
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};
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static inline struct visconti_pwm_chip *visconti_pwm_from_chip(struct pwm_chip *chip)
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{
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return container_of(chip, struct visconti_pwm_chip, chip);
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}
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static int visconti_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
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const struct pwm_state *state)
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{
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struct visconti_pwm_chip *priv = visconti_pwm_from_chip(chip);
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u32 period, duty_cycle, pwmc0;
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if (!state->enabled) {
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writel(0, priv->base + PIPGM_PCSR(pwm->hwpwm));
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return 0;
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}
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/*
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* The biggest period the hardware can provide is
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* (0xffff << 3) * 1000 ns
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* This value fits easily in an u32, so simplify the maths by
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* capping the values to 32 bit integers.
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*/
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if (state->period > (0xffff << 3) * 1000)
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period = (0xffff << 3) * 1000;
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else
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period = state->period;
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if (state->duty_cycle > period)
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duty_cycle = period;
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else
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duty_cycle = state->duty_cycle;
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/*
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* The input clock runs fixed at 1 MHz, so we have only
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* microsecond resolution and so can divide by
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* NSEC_PER_SEC / CLKFREQ = 1000 without losing precision.
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*/
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period /= 1000;
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duty_cycle /= 1000;
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if (!period)
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return -ERANGE;
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/*
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* PWMC controls a divider that divides the input clk by a
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* power of two between 1 and 8. As a smaller divider yields
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* higher precision, pick the smallest possible one.
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*/
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if (period > 0xffff) {
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pwmc0 = ilog2(period >> 16);
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if (WARN_ON(pwmc0 > 3))
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return -EINVAL;
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} else {
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pwmc0 = 0;
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}
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period >>= pwmc0;
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duty_cycle >>= pwmc0;
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if (state->polarity == PWM_POLARITY_INVERSED)
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pwmc0 |= PIPGM_PWMC_PWMACT;
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writel(pwmc0, priv->base + PIPGM_PWMC(pwm->hwpwm));
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writel(duty_cycle, priv->base + PIPGM_PDUT(pwm->hwpwm));
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writel(period, priv->base + PIPGM_PCSR(pwm->hwpwm));
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return 0;
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}
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static void visconti_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
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struct pwm_state *state)
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{
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struct visconti_pwm_chip *priv = visconti_pwm_from_chip(chip);
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u32 period, duty, pwmc0, pwmc0_clk;
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period = readl(priv->base + PIPGM_PCSR(pwm->hwpwm));
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duty = readl(priv->base + PIPGM_PDUT(pwm->hwpwm));
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pwmc0 = readl(priv->base + PIPGM_PWMC(pwm->hwpwm));
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pwmc0_clk = pwmc0 & PIPGM_PWMC_CLK_MASK;
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state->period = (period << pwmc0_clk) * NSEC_PER_USEC;
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state->duty_cycle = (duty << pwmc0_clk) * NSEC_PER_USEC;
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if (pwmc0 & PIPGM_PWMC_POLARITY_MASK)
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state->polarity = PWM_POLARITY_INVERSED;
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else
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state->polarity = PWM_POLARITY_NORMAL;
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state->enabled = true;
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}
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static const struct pwm_ops visconti_pwm_ops = {
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.apply = visconti_pwm_apply,
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.get_state = visconti_pwm_get_state,
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.owner = THIS_MODULE,
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};
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static int visconti_pwm_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct visconti_pwm_chip *priv;
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int ret;
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priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
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if (!priv)
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return -ENOMEM;
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priv->base = devm_platform_ioremap_resource(pdev, 0);
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if (IS_ERR(priv->base))
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return PTR_ERR(priv->base);
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platform_set_drvdata(pdev, priv);
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priv->chip.dev = dev;
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priv->chip.ops = &visconti_pwm_ops;
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priv->chip.npwm = 4;
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ret = pwmchip_add(&priv->chip);
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if (ret < 0)
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return dev_err_probe(&pdev->dev, ret, "Cannot register visconti PWM\n");
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return 0;
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}
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static int visconti_pwm_remove(struct platform_device *pdev)
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{
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struct visconti_pwm_chip *priv = platform_get_drvdata(pdev);
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pwmchip_remove(&priv->chip);
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return 0;
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}
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static const struct of_device_id visconti_pwm_of_match[] = {
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{ .compatible = "toshiba,visconti-pwm", },
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{ }
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};
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MODULE_DEVICE_TABLE(of, visconti_pwm_of_match);
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static struct platform_driver visconti_pwm_driver = {
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.driver = {
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.name = "pwm-visconti",
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.of_match_table = visconti_pwm_of_match,
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},
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.probe = visconti_pwm_probe,
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.remove = visconti_pwm_remove,
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};
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module_platform_driver(visconti_pwm_driver);
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MODULE_LICENSE("GPL v2");
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MODULE_AUTHOR("Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>");
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MODULE_ALIAS("platform:pwm-visconti");
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