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![YH Huang](/assets/img/avatar_default.png)
Add display PWM driver support to modify backlight for MT8173 and MT6595. The PWM has one channel to control the brightness of the display. When the (high_width / period) is closer to 1, the screen is brighter; otherwise, it is darker. Signed-off-by: YH Huang <yh.huang@mediatek.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
243 lines
6 KiB
C
243 lines
6 KiB
C
/*
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* MediaTek display pulse-width-modulation controller driver.
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* Copyright (c) 2015 MediaTek Inc.
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* Author: YH Huang <yh.huang@mediatek.com>
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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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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <linux/clk.h>
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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.h>
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#include <linux/platform_device.h>
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#include <linux/pwm.h>
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#include <linux/slab.h>
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#define DISP_PWM_EN 0x00
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#define PWM_ENABLE_MASK BIT(0)
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#define DISP_PWM_COMMIT 0x08
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#define PWM_COMMIT_MASK BIT(0)
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#define DISP_PWM_CON_0 0x10
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#define PWM_CLKDIV_SHIFT 16
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#define PWM_CLKDIV_MAX 0x3ff
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#define PWM_CLKDIV_MASK (PWM_CLKDIV_MAX << PWM_CLKDIV_SHIFT)
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#define DISP_PWM_CON_1 0x14
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#define PWM_PERIOD_BIT_WIDTH 12
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#define PWM_PERIOD_MASK ((1 << PWM_PERIOD_BIT_WIDTH) - 1)
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#define PWM_HIGH_WIDTH_SHIFT 16
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#define PWM_HIGH_WIDTH_MASK (0x1fff << PWM_HIGH_WIDTH_SHIFT)
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struct mtk_disp_pwm {
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struct pwm_chip chip;
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struct clk *clk_main;
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struct clk *clk_mm;
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void __iomem *base;
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};
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static inline struct mtk_disp_pwm *to_mtk_disp_pwm(struct pwm_chip *chip)
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{
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return container_of(chip, struct mtk_disp_pwm, chip);
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}
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static void mtk_disp_pwm_update_bits(struct mtk_disp_pwm *mdp, u32 offset,
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u32 mask, u32 data)
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{
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void __iomem *address = mdp->base + offset;
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u32 value;
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value = readl(address);
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value &= ~mask;
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value |= data;
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writel(value, address);
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}
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static int mtk_disp_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
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int duty_ns, int period_ns)
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{
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struct mtk_disp_pwm *mdp = to_mtk_disp_pwm(chip);
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u32 clk_div, period, high_width, value;
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u64 div, rate;
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int err;
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/*
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* Find period, high_width and clk_div to suit duty_ns and period_ns.
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* Calculate proper div value to keep period value in the bound.
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*
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* period_ns = 10^9 * (clk_div + 1) * (period + 1) / PWM_CLK_RATE
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* duty_ns = 10^9 * (clk_div + 1) * high_width / PWM_CLK_RATE
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*
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* period = (PWM_CLK_RATE * period_ns) / (10^9 * (clk_div + 1)) - 1
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* high_width = (PWM_CLK_RATE * duty_ns) / (10^9 * (clk_div + 1))
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*/
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rate = clk_get_rate(mdp->clk_main);
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clk_div = div_u64(rate * period_ns, NSEC_PER_SEC) >>
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PWM_PERIOD_BIT_WIDTH;
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if (clk_div > PWM_CLKDIV_MAX)
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return -EINVAL;
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div = NSEC_PER_SEC * (clk_div + 1);
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period = div64_u64(rate * period_ns, div);
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if (period > 0)
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period--;
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high_width = div64_u64(rate * duty_ns, div);
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value = period | (high_width << PWM_HIGH_WIDTH_SHIFT);
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err = clk_enable(mdp->clk_main);
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if (err < 0)
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return err;
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err = clk_enable(mdp->clk_mm);
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if (err < 0) {
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clk_disable(mdp->clk_main);
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return err;
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}
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mtk_disp_pwm_update_bits(mdp, DISP_PWM_CON_0, PWM_CLKDIV_MASK,
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clk_div << PWM_CLKDIV_SHIFT);
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mtk_disp_pwm_update_bits(mdp, DISP_PWM_CON_1,
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PWM_PERIOD_MASK | PWM_HIGH_WIDTH_MASK, value);
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mtk_disp_pwm_update_bits(mdp, DISP_PWM_COMMIT, PWM_COMMIT_MASK, 1);
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mtk_disp_pwm_update_bits(mdp, DISP_PWM_COMMIT, PWM_COMMIT_MASK, 0);
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clk_disable(mdp->clk_mm);
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clk_disable(mdp->clk_main);
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return 0;
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}
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static int mtk_disp_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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struct mtk_disp_pwm *mdp = to_mtk_disp_pwm(chip);
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int err;
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err = clk_enable(mdp->clk_main);
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if (err < 0)
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return err;
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err = clk_enable(mdp->clk_mm);
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if (err < 0) {
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clk_disable(mdp->clk_main);
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return err;
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}
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mtk_disp_pwm_update_bits(mdp, DISP_PWM_EN, PWM_ENABLE_MASK, 1);
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return 0;
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}
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static void mtk_disp_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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struct mtk_disp_pwm *mdp = to_mtk_disp_pwm(chip);
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mtk_disp_pwm_update_bits(mdp, DISP_PWM_EN, PWM_ENABLE_MASK, 0);
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clk_disable(mdp->clk_mm);
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clk_disable(mdp->clk_main);
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}
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static const struct pwm_ops mtk_disp_pwm_ops = {
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.config = mtk_disp_pwm_config,
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.enable = mtk_disp_pwm_enable,
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.disable = mtk_disp_pwm_disable,
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.owner = THIS_MODULE,
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};
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static int mtk_disp_pwm_probe(struct platform_device *pdev)
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{
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struct mtk_disp_pwm *mdp;
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struct resource *r;
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int ret;
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mdp = devm_kzalloc(&pdev->dev, sizeof(*mdp), GFP_KERNEL);
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if (!mdp)
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return -ENOMEM;
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r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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mdp->base = devm_ioremap_resource(&pdev->dev, r);
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if (IS_ERR(mdp->base))
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return PTR_ERR(mdp->base);
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mdp->clk_main = devm_clk_get(&pdev->dev, "main");
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if (IS_ERR(mdp->clk_main))
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return PTR_ERR(mdp->clk_main);
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mdp->clk_mm = devm_clk_get(&pdev->dev, "mm");
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if (IS_ERR(mdp->clk_mm))
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return PTR_ERR(mdp->clk_mm);
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ret = clk_prepare(mdp->clk_main);
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if (ret < 0)
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return ret;
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ret = clk_prepare(mdp->clk_mm);
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if (ret < 0)
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goto disable_clk_main;
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mdp->chip.dev = &pdev->dev;
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mdp->chip.ops = &mtk_disp_pwm_ops;
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mdp->chip.base = -1;
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mdp->chip.npwm = 1;
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ret = pwmchip_add(&mdp->chip);
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if (ret < 0) {
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dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
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goto disable_clk_mm;
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}
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platform_set_drvdata(pdev, mdp);
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return 0;
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disable_clk_mm:
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clk_unprepare(mdp->clk_mm);
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disable_clk_main:
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clk_unprepare(mdp->clk_main);
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return ret;
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}
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static int mtk_disp_pwm_remove(struct platform_device *pdev)
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{
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struct mtk_disp_pwm *mdp = platform_get_drvdata(pdev);
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int ret;
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ret = pwmchip_remove(&mdp->chip);
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clk_unprepare(mdp->clk_mm);
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clk_unprepare(mdp->clk_main);
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return ret;
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}
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static const struct of_device_id mtk_disp_pwm_of_match[] = {
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{ .compatible = "mediatek,mt8173-disp-pwm" },
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{ .compatible = "mediatek,mt6595-disp-pwm" },
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{ }
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};
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MODULE_DEVICE_TABLE(of, mtk_disp_pwm_of_match);
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static struct platform_driver mtk_disp_pwm_driver = {
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.driver = {
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.name = "mediatek-disp-pwm",
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.of_match_table = mtk_disp_pwm_of_match,
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},
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.probe = mtk_disp_pwm_probe,
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.remove = mtk_disp_pwm_remove,
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};
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module_platform_driver(mtk_disp_pwm_driver);
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MODULE_AUTHOR("YH Huang <yh.huang@mediatek.com>");
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MODULE_DESCRIPTION("MediaTek SoC display PWM driver");
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MODULE_LICENSE("GPL v2");
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