Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751991AbaJBLli (ORCPT ); Thu, 2 Oct 2014 07:41:38 -0400 Received: from albert.telenet-ops.be ([195.130.137.90]:38559 "EHLO albert.telenet-ops.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751176AbaJBLlh (ORCPT ); Thu, 2 Oct 2014 07:41:37 -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: [resend rfc v5]pwm: add BCM2835 PWM driver Date: Thu, 2 Oct 2014 13:41:15 +0200 Message-Id: <1412250075-3082-1-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 --- Changes in v5: - add the correct copyright comments according the university college philosophy - better error handling - use devm clk lookup - define some variables - add the clock description diff --git a/Documentation/devicetree/bindings/pwm/pwm-bcm2835.txt b/Documentation/devicetree/bindings/pwm/pwm-bcm2835.txt new file mode 100644 index 0000000..eea1e8c --- /dev/null +++ b/Documentation/devicetree/bindings/pwm/pwm-bcm2835.txt @@ -0,0 +1,24 @@ +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 + +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 22f2f28..a277256 100644 --- a/drivers/pwm/Kconfig +++ b/drivers/pwm/Kconfig @@ -62,6 +62,15 @@ config PWM_ATMEL_TCB To compile this driver as a module, choose M here: the module will be called pwm-atmel-tcb. +config PWM_BCM2835 + tristate "BCM2835 PWM support" + depends on MACH_BCM2835 || MACH_BCM2708 + 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/Makefile b/drivers/pwm/Makefile index d8906ec..9863590 100644 --- a/drivers/pwm/Makefile +++ b/drivers/pwm/Makefile @@ -3,6 +3,7 @@ obj-$(CONFIG_PWM_SYSFS) += sysfs.o obj-$(CONFIG_PWM_AB8500) += pwm-ab8500.o obj-$(CONFIG_PWM_ATMEL) += pwm-atmel.o obj-$(CONFIG_PWM_ATMEL_TCB) += pwm-atmel-tcb.o +obj-$(CONFIG_PWM_BCM2835) += pwm-bcm2835.o obj-$(CONFIG_PWM_BFIN) += pwm-bfin.o obj-$(CONFIG_PWM_EP93XX) += pwm-ep93xx.o obj-$(CONFIG_PWM_IMX) += pwm-imx.o diff --git a/drivers/pwm/pwm-bcm2835.c b/drivers/pwm/pwm-bcm2835.c new file mode 100644 index 0000000..eaf1876 --- /dev/null +++ b/drivers/pwm/pwm-bcm2835.c @@ -0,0 +1,204 @@ +/* + * 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 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->pwm); + value |= (PWM_MODE << (PWM_CONTROL_STRIDE * pwm->pwm)); + 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 &= ~(PWM_CONTROL_MASK << PWM_CONTROL_STRIDE * pwm->pwm); + value &= (~DEFAULT << (PWM_CONTROL_STRIDE * pwm->pwm)); + 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; + } else { + writel(duty_ns / pc->scaler, + pc->base + DUTY + pwm->pwm * CHANNEL); + writel(period_ns / pc->scaler, + pc->base + PERIOD + pwm->pwm * 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->pwm)); + 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->pwm)); + 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; + + if (polarity == PWM_POLARITY_NORMAL) { + value = readl(pc->base); + value &= ~(PWM_POLARITY << PWM_CONTROL_STRIDE * pwm->pwm); + } else if (polarity == PWM_POLARITY_INVERSED) { + value = readl(pc->base); + value |= PWM_POLARITY << (PWM_CONTROL_STRIDE * pwm->pwm); + } + 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; + + 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); + + 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); + + 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) { + dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret); + return ret; + } + return 0; +} + +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