Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755712AbaJHKOY (ORCPT ); Wed, 8 Oct 2014 06:14:24 -0400 Received: from michel.telenet-ops.be ([195.130.137.88]:50076 "EHLO michel.telenet-ops.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754718AbaJHKOX (ORCPT ); Wed, 8 Oct 2014 06:14:23 -0400 From: Bart Tanghe To: thierry.reding@gmail.com Cc: matt.porter@linaro.org, linux-kernel@vger.kernel.org, linux-pwm@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, bart.tanghe@thomasmore.be Subject: [PATCH v7]pwm: add BCM2835 PWM driver Date: Wed, 8 Oct 2014 12:14:32 +0200 Message-Id: <1412763272-24269-1-git-send-email-bart.tanghe@thomasmore.be> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add pwm driver for Broadcom BCM2835 processor (Raspberry Pi) Signed-off-by: Bart Tanghe --- Changed in v7: - clean up the shameful clk_enable error handling introduced in v6 - clean up the code nits diff --git a/Documentation/devicetree/bindings/pwm/pwm-bcm2835.txt b/Documentation/devicetree/bindings/pwm/pwm-bcm2835.txt new file mode 100644 index 0000000..d5162db --- /dev/null +++ b/Documentation/devicetree/bindings/pwm/pwm-bcm2835.txt @@ -0,0 +1,27 @@ +BCM2835 PWM controller (Raspberry Pi controller) + +Required properties: +- compatible: should be "brcm,bcm2835-pwm" +- reg: physical base address and length of the controller's registers +- clock: this clock defines the base clock frequency of the pwm +hardware system, the period and the duty_cycle of the pwm signal is a +multiple of the base period + +Examples: + +pwm@2020c000 { + compatible = "brcm,bcm2835-pwm"; + reg = <0x2020c000 0x28>; + clocks = <&clk_pwm>; +}; + +clocks { + .... + clk_pwm: pwm { + compatible = "fixed-clock"; + reg = <3>; + #clock-cells = <0>; + clock-frequency = <9200000>; + }; + .... +}; diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig index 90c5c73..e533178 100644 --- a/drivers/pwm/Kconfig +++ b/drivers/pwm/Kconfig @@ -29,6 +29,15 @@ menuconfig PWM if PWM +config PWM_BCM2835 + tristate "BCM2835 PWM support" + depends on ARCH_BCM2835 + help + PWM framework driver for BCM2835 controller (Raspberry Pi) + + To compile this driver as a module, choose M here: the module + will be called pwm-bcm2835 + config PWM_BFIN tristate "Blackfin PWM support" depends on BFIN_GPTIMERS diff --git a/drivers/pwm/pwm-bcm2835.c b/drivers/pwm/pwm-bcm2835.c new file mode 100644 index 0000000..99dc073 --- /dev/null +++ b/drivers/pwm/pwm-bcm2835.c @@ -0,0 +1,202 @@ +/* + * Copyright 2014 Bart Tanghe + * + * 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; version 2. + */ + +#include +#include +#include +#include +#include +#include +#include + +#define DUTY 0x14 +#define PERIOD 0x10 +#define CHANNEL 0x10 + +#define PWM_ENABLE (1 << 0) +#define PWM_POLARITY (1 << 4) + +#define PWM_CONTROL_MASK 0xff +#define PWM_MODE 0x80 /* set timer in pwm mode */ +#define DEFAULT_PWM_MODE 0xff /* set timer in default mode */ +#define PWM_CONTROL_STRIDE 8 +#define MIN_PERIOD 108 /* 9.2Mhz max pwm clock */ + +struct bcm2835_pwm { + struct pwm_chip chip; + struct device *dev; + int channel; + unsigned long scaler; + void __iomem *base; + struct clk *clk; +}; + +static inline struct bcm2835_pwm *to_bcm2835_pwm(struct pwm_chip *chip) +{ + return container_of(chip, struct bcm2835_pwm, chip); +} + +static int bcm2835_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); + u32 value; + + value = readl(pc->base); + value &= ~(PWM_CONTROL_MASK << (PWM_CONTROL_STRIDE * pwm->hwpwm)); + value |= (PWM_MODE << (PWM_CONTROL_STRIDE * pwm->hwpwm)); + writel(value, pc->base); + return 0; +} + +static void bcm2835_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); + u32 value; + + value = readl(pc->base); + value &= (~DEFAULT_PWM_MODE << (PWM_CONTROL_STRIDE * pwm->hwpwm)); + writel(value, pc->base); +} + +static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, + int duty_ns, int period_ns) +{ + struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); + + if (period_ns <= MIN_PERIOD) { + dev_err(pc->dev, "Period not supported\n"); + return -EINVAL; + } + writel(duty_ns / pc->scaler, pc->base + DUTY + pwm->hwpwm * CHANNEL); + writel(period_ns / pc->scaler, + pc->base + PERIOD + pwm->hwpwm * CHANNEL); + return 0; +} + +static int bcm2835_pwm_enable(struct pwm_chip *chip, + struct pwm_device *pwm) +{ + struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); + u32 value; + + value = readl(pc->base); + value |= PWM_ENABLE << (PWM_CONTROL_STRIDE * pwm->hwpwm); + writel(value, pc->base); + return 0; +} + +static void bcm2835_pwm_disable(struct pwm_chip *chip, + struct pwm_device *pwm) +{ + struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); + u32 value; + + value = readl(pc->base); + value &= ~(PWM_ENABLE << (PWM_CONTROL_STRIDE * pwm->hwpwm)); + writel(value, pc->base); +} + +static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, + enum pwm_polarity polarity) +{ + struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); + u32 value; + + value = readl(pc->base); + if (polarity == PWM_POLARITY_NORMAL) + value &= ~(PWM_POLARITY << (PWM_CONTROL_STRIDE * pwm->hwpwm)); + else if (polarity == PWM_POLARITY_INVERSED) + value |= PWM_POLARITY << (PWM_CONTROL_STRIDE * pwm->hwpwm); + writel(value, pc->base); + return 0; +} + +static const struct pwm_ops bcm2835_pwm_ops = { + .request = bcm2835_pwm_request, + .free = bcm2835_pwm_free, + .config = bcm2835_pwm_config, + .enable = bcm2835_pwm_enable, + .disable = bcm2835_pwm_disable, + .set_polarity = bcm2835_set_polarity, + .owner = THIS_MODULE, +}; + +static int bcm2835_pwm_probe(struct platform_device *pdev) +{ + struct bcm2835_pwm *pwm; + int ret; + struct resource *r; + struct clk *clk; + + 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->base = devm_ioremap_resource(&pdev->dev, r); + if (IS_ERR(pwm->base)) + return PTR_ERR(pwm->base); + + clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(clk)) { + dev_err(&pdev->dev, "no clock found: %ld\n", PTR_ERR(clk)); + return PTR_ERR(clk); + } + + pwm->clk = clk; + ret = clk_prepare_enable(pwm->clk); + if (ret) + return ret; + + pwm->scaler = NSEC_PER_SEC / clk_get_rate(clk); + + pwm->chip.dev = &pdev->dev; + pwm->chip.ops = &bcm2835_pwm_ops; + pwm->chip.npwm = 2; + + platform_set_drvdata(pdev, pwm); + + ret = pwmchip_add(&pwm->chip); + if (ret < 0) + goto add_fail; + + return 0; + +add_fail: + clk_disable_unprepare(pwm->clk); + return ret; +} + +static int bcm2835_pwm_remove(struct platform_device *pdev) +{ + struct bcm2835_pwm *pc = platform_get_drvdata(pdev); + clk_disable_unprepare(pc->clk); + return pwmchip_remove(&pc->chip); +} + +static const struct of_device_id bcm2835_pwm_of_match[] = { + { .compatible = "brcm,bcm2835-pwm", }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, bcm2835_pwm_of_match); + +static struct platform_driver bcm2835_pwm_driver = { + .driver = { + .name = "bcm2835-pwm", + .of_match_table = bcm2835_pwm_of_match, + }, + .probe = bcm2835_pwm_probe, + .remove = bcm2835_pwm_remove, +}; +module_platform_driver(bcm2835_pwm_driver); + +MODULE_AUTHOR("Bart Tanghe