Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932539AbbELMh1 (ORCPT ); Tue, 12 May 2015 08:37:27 -0400 Received: from mail-lb0-f173.google.com ([209.85.217.173]:35264 "EHLO mail-lb0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752835AbbELMhY (ORCPT ); Tue, 12 May 2015 08:37:24 -0400 MIME-Version: 1.0 In-Reply-To: <1431336382-13167-3-git-send-email-yh.huang@mediatek.com> References: <1431336382-13167-1-git-send-email-yh.huang@mediatek.com> <1431336382-13167-3-git-send-email-yh.huang@mediatek.com> Date: Tue, 12 May 2015 14:37:22 +0200 Message-ID: Subject: Re: [PATCH 2/2] pwm: add Mediatek display PWM driver support From: Matthias Brugger To: YH Huang Cc: Mark Rutland , Thierry Reding , Rob Herring , Pawel Moll , linux-pwm@vger.kernel.org, "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , srv_heupstream , linux-mediatek@lists.infradead.org, Sascha Hauer Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8642 Lines: 230 Hi YH, 2015-05-11 11:26 GMT+02:00 YH Huang : > Add display PWM driver support to modify backlight for MT8173/MT6595. > > Signed-off-by: YH Huang > --- > drivers/pwm/Kconfig | 9 ++ > drivers/pwm/Makefile | 1 + > drivers/pwm/pwm-disp-mediatek.c | 225 ++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 235 insertions(+) > create mode 100644 drivers/pwm/pwm-disp-mediatek.c > > diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig > index b1541f4..9edbb5a 100644 > --- a/drivers/pwm/Kconfig > +++ b/drivers/pwm/Kconfig > @@ -111,6 +111,15 @@ config PWM_CLPS711X > To compile this driver as a module, choose M here: the module > will be called pwm-clps711x. > > +config PWM_DISP_MEDIATEK > + tristate "MEDIATEK display PWM driver" > + depends on OF > + help > + Generic PWM framework driver for mediatek disp-pwm device. > + > + To compile this driver as a module, choose M here: the module > + will be called pwm-disp-mediatek. > + > config PWM_EP93XX > tristate "Cirrus Logic EP93xx PWM support" > depends on ARCH_EP93XX > diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile > index ec50eb5..c5ff72a 100644 > --- a/drivers/pwm/Makefile > +++ b/drivers/pwm/Makefile > @@ -8,6 +8,7 @@ obj-$(CONFIG_PWM_BCM_KONA) += pwm-bcm-kona.o > obj-$(CONFIG_PWM_BCM2835) += pwm-bcm2835.o > obj-$(CONFIG_PWM_BFIN) += pwm-bfin.o > obj-$(CONFIG_PWM_CLPS711X) += pwm-clps711x.o > +obj-$(CONFIG_PWM_DISP_MEDIATEK) += pwm-disp-mediatek.o > obj-$(CONFIG_PWM_EP93XX) += pwm-ep93xx.o > obj-$(CONFIG_PWM_FSL_FTM) += pwm-fsl-ftm.o > obj-$(CONFIG_PWM_IMG) += pwm-img.o > diff --git a/drivers/pwm/pwm-disp-mediatek.c b/drivers/pwm/pwm-disp-mediatek.c > new file mode 100644 > index 0000000..38293af > --- /dev/null > +++ b/drivers/pwm/pwm-disp-mediatek.c > @@ -0,0 +1,225 @@ > +/* > + * Mediatek display pulse-width-modulation controller driver. > + * Copyright (c) 2015 MediaTek Inc. > + * Author: YH Huang > + * > + * 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. > + * > + * 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 > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#define DISP_PWM_EN_OFF (0x0) > +#define PWM_ENABLE_SHIFT (0x0) > +#define PWM_ENABLE_MASK (0x1 << PWM_ENABLE_SHIFT) Get rid of the _SHIFT which are actually zero, it will make the code more readable. > + > +#define DISP_PWM_COMMIT_OFF (0x08) > +#define PWM_COMMIT_SHIFT (0x0) > +#define PWM_COMMIT_MASK (0x1 << PWM_COMMIT_SHIFT) > + > +#define DISP_PWM_CON_0_OFF (0x10) > +#define PWM_CLKDIV_SHIFT (0x10) > +#define PWM_CLKDIV_MASK (0x3ff << PWM_CLKDIV_SHIFT) > +#define PWM_CLKDIV_MAX (0x000003ff) > + > +#define DISP_PWM_CON_1_OFF (0x14) > +#define PWM_PERIOD_SHIFT (0x0) > +#define PWM_PERIOD_MASK (0xfff << PWM_PERIOD_SHIFT) > +#define PWM_PERIOD_MAX (0x00000fff) > +/* Shift log2(PWM_PERIOD_MAX + 1) as divisor */ > +#define PWM_PERIOD_BIT_SHIFT 12 > + > +#define PWM_HIGH_WIDTH_SHIFT (0x10) > +#define PWM_HIGH_WIDTH_MASK (0x1fff << PWM_HIGH_WIDTH_SHIFT) > + > +#define NUM_PWM 1 > + > +struct mtk_disp_pwm_chip { > + struct pwm_chip chip; > + struct device *dev; > + struct clk *clk_main; > + struct clk *clk_mm; > + void __iomem *mmio_base; > +}; > + > +static void mtk_disp_pwm_setting(void __iomem *address, u32 value, u32 mask) > +{ > + u32 val; > + > + val = readl(address); > + val &= ~mask; > + val |= value; > + writel(val, address); > +} > + > +static int mtk_disp_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, > + int duty_ns, int period_ns) > +{ > + struct mtk_disp_pwm_chip *mpc; > + u64 div, rate; > + u32 clk_div, period, high_width, rem; > + > + /* > + * Find period, high_width and clk_div to suit duty_ns and period_ns. > + * Calculate proper div value to keep period value in the bound. > + * > + * period_ns = 10^9 * (clk_div + 1) * (period +1) / PWM_CLK_RATE > + * duty_ns = 10^9 * (clk_div + 1) * (high_width + 1) / PWM_CLK_RATE > + * > + * period = (PWM_CLK_RATE * period_ns) / (10^9 * (clk_div + 1)) - 1 > + * high_width = (PWM_CLK_RATE * duty_ns) / (10^9 * (clk_div + 1)) - 1 > + */ > + mpc = container_of(chip, struct mtk_disp_pwm_chip, chip); > + rate = clk_get_rate(mpc->clk_main); > + clk_div = div_u64_rem(rate * period_ns, NSEC_PER_SEC, &rem) >> > + PWM_PERIOD_BIT_SHIFT; You never use the remainder, so better use div_u64 to make the code cleaner. > + if (clk_div > PWM_CLKDIV_MAX) > + return -EINVAL; > + > + div = clk_div + 1; > + period = div64_u64(rate * period_ns, NSEC_PER_SEC * div); > + if (period > 0) > + period--; > + high_width = div64_u64(rate * duty_ns, NSEC_PER_SEC * div); > + if (high_width > 0) > + high_width--; > + > + mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_CON_0_OFF, > + clk_div << PWM_CLKDIV_SHIFT, PWM_CLKDIV_MASK); > + mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_CON_1_OFF, > + (period << PWM_PERIOD_SHIFT) | > + (high_width << PWM_HIGH_WIDTH_SHIFT), > + PWM_PERIOD_MASK | PWM_HIGH_WIDTH_MASK); > + > + mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_COMMIT_OFF, > + 1 << PWM_COMMIT_SHIFT, PWM_COMMIT_MASK); > + mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_COMMIT_OFF, > + 0 << PWM_COMMIT_SHIFT, PWM_COMMIT_MASK); > + > + return 0; > +} > + > +static int mtk_disp_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) > +{ > + struct mtk_disp_pwm_chip *mpc; > + > + mpc = container_of(chip, struct mtk_disp_pwm_chip, chip); > + mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_EN_OFF, > + 1 << PWM_ENABLE_SHIFT, PWM_ENABLE_MASK); > + > + return 0; > +} > + > +static void mtk_disp_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) > +{ > + struct mtk_disp_pwm_chip *mpc; > + > + mpc = container_of(chip, struct mtk_disp_pwm_chip, chip); > + mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_EN_OFF, > + 0 << PWM_ENABLE_SHIFT, PWM_ENABLE_MASK); > +} > + > +static const struct pwm_ops mtk_disp_pwm_ops = { > + .config = mtk_disp_pwm_config, > + .enable = mtk_disp_pwm_enable, > + .disable = mtk_disp_pwm_disable, > + .owner = THIS_MODULE, > +}; > + > +static int mtk_disp_pwm_probe(struct platform_device *pdev) > +{ > + struct mtk_disp_pwm_chip *pwm; > + struct resource *r; > + int ret; > + > + pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL); > + if (!pwm) > + return -ENOMEM; > + > + pwm->dev = &pdev->dev; > + > + r = platform_get_resource(pdev, IORESOURCE_MEM, 0); > + pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r); > + if (IS_ERR(pwm->mmio_base)) > + return PTR_ERR(pwm->mmio_base); > + > + pwm->clk_main = devm_clk_get(&pdev->dev, "main"); > + if (IS_ERR(pwm->clk_main)) > + return PTR_ERR(pwm->clk_main); I prefer to have a newline after the if-then-ese block, which makes it (at least for me) easier to read the code. Thanks, Matthias -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/