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a05af71f0d
The CRC PWM controller has a clock-divider which divides the clock with a value between 1-128. But as can seen from the PWM_DIV_CLK_xxx defines, this range maps to a register value of 0-127. So after calculating the clock-divider we must subtract 1 to get the register value, unless the requested frequency was so high that the calculation has already resulted in a (rounded) divider value of 0. Note that before this fix, setting a period of PWM_MAX_PERIOD_NS which corresponds to the max. divider value of 128 could have resulted in a bug where the code would use 128 as divider-register value which would have resulted in an actual divider value of 0 (and the enable bit being set). A rounding error stopped this bug from actually happen. This same rounding error means that after the subtraction of 1 it is impossible to set the divider to 128. Also bump PWM_MAX_PERIOD_NS by 1 ns to allow setting a divider of 128 (register-value 127). Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Acked-by: Thierry Reding <thierry.reding@gmail.com> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200903112337.4113-10-hdegoede@redhat.com
146 lines
3.4 KiB
C
146 lines
3.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2015 Intel Corporation. All rights reserved.
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*
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* Author: Shobhit Kumar <shobhit.kumar@intel.com>
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*/
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#include <linux/platform_device.h>
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#include <linux/regmap.h>
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#include <linux/mfd/intel_soc_pmic.h>
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#include <linux/pwm.h>
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#define PWM0_CLK_DIV 0x4B
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#define PWM_OUTPUT_ENABLE BIT(7)
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#define PWM_DIV_CLK_0 0x00 /* DIVIDECLK = BASECLK */
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#define PWM_DIV_CLK_100 0x63 /* DIVIDECLK = BASECLK/100 */
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#define PWM_DIV_CLK_128 0x7F /* DIVIDECLK = BASECLK/128 */
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#define PWM0_DUTY_CYCLE 0x4E
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#define BACKLIGHT_EN 0x51
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#define PWM_MAX_LEVEL 0xFF
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#define PWM_BASE_CLK_MHZ 6 /* 6 MHz */
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#define PWM_MAX_PERIOD_NS 5461334 /* 183 Hz */
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/**
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* struct crystalcove_pwm - Crystal Cove PWM controller
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* @chip: the abstract pwm_chip structure.
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* @regmap: the regmap from the parent device.
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*/
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struct crystalcove_pwm {
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struct pwm_chip chip;
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struct regmap *regmap;
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};
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static inline struct crystalcove_pwm *to_crc_pwm(struct pwm_chip *pc)
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{
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return container_of(pc, struct crystalcove_pwm, chip);
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}
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static int crc_pwm_calc_clk_div(int period_ns)
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{
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int clk_div;
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clk_div = PWM_BASE_CLK_MHZ * period_ns / (256 * NSEC_PER_USEC);
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/* clk_div 1 - 128, maps to register values 0-127 */
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if (clk_div > 0)
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clk_div--;
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return clk_div;
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}
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static int crc_pwm_enable(struct pwm_chip *c, struct pwm_device *pwm)
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{
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struct crystalcove_pwm *crc_pwm = to_crc_pwm(c);
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regmap_write(crc_pwm->regmap, BACKLIGHT_EN, 1);
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return 0;
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}
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static void crc_pwm_disable(struct pwm_chip *c, struct pwm_device *pwm)
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{
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struct crystalcove_pwm *crc_pwm = to_crc_pwm(c);
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regmap_write(crc_pwm->regmap, BACKLIGHT_EN, 0);
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}
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static int crc_pwm_config(struct pwm_chip *c, struct pwm_device *pwm,
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int duty_ns, int period_ns)
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{
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struct crystalcove_pwm *crc_pwm = to_crc_pwm(c);
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struct device *dev = crc_pwm->chip.dev;
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int level;
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if (period_ns > PWM_MAX_PERIOD_NS) {
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dev_err(dev, "un-supported period_ns\n");
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return -EINVAL;
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}
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if (pwm_get_period(pwm) != period_ns) {
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int clk_div = crc_pwm_calc_clk_div(period_ns);
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/* changing the clk divisor, need to disable fisrt */
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crc_pwm_disable(c, pwm);
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regmap_write(crc_pwm->regmap, PWM0_CLK_DIV,
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clk_div | PWM_OUTPUT_ENABLE);
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/* enable back */
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crc_pwm_enable(c, pwm);
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}
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/* change the pwm duty cycle */
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level = duty_ns * PWM_MAX_LEVEL / period_ns;
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regmap_write(crc_pwm->regmap, PWM0_DUTY_CYCLE, level);
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return 0;
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}
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static const struct pwm_ops crc_pwm_ops = {
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.config = crc_pwm_config,
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.enable = crc_pwm_enable,
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.disable = crc_pwm_disable,
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};
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static int crystalcove_pwm_probe(struct platform_device *pdev)
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{
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struct crystalcove_pwm *pwm;
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struct device *dev = pdev->dev.parent;
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struct intel_soc_pmic *pmic = dev_get_drvdata(dev);
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pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
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if (!pwm)
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return -ENOMEM;
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pwm->chip.dev = &pdev->dev;
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pwm->chip.ops = &crc_pwm_ops;
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pwm->chip.base = -1;
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pwm->chip.npwm = 1;
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/* get the PMIC regmap */
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pwm->regmap = pmic->regmap;
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platform_set_drvdata(pdev, pwm);
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return pwmchip_add(&pwm->chip);
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}
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static int crystalcove_pwm_remove(struct platform_device *pdev)
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{
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struct crystalcove_pwm *pwm = platform_get_drvdata(pdev);
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return pwmchip_remove(&pwm->chip);
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}
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static struct platform_driver crystalcove_pwm_driver = {
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.probe = crystalcove_pwm_probe,
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.remove = crystalcove_pwm_remove,
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.driver = {
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.name = "crystal_cove_pwm",
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},
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};
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builtin_platform_driver(crystalcove_pwm_driver);
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