Add support for the PWM controller of the BCM2835 SoC found on Raspberry PI
The driver isn't as much tested as I wanted it to be and devicetree support is still missing, but I thought it would be nice to have some comments if I'm in the right direction. Signed-off-by: Johannes Thumshirn <morbid...@gmail.com> --- drivers/pwm/Kconfig | 8 ++ drivers/pwm/Makefile | 1 + drivers/pwm/pwm-bcm2835.c | 275 ++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 284 insertions(+) create mode 100644 drivers/pwm/pwm-bcm2835.c diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig index 75840b5..5417159 100644 --- a/drivers/pwm/Kconfig +++ b/drivers/pwm/Kconfig @@ -224,4 +224,12 @@ config PWM_VT8500 To compile this driver as a module, choose M here: the module will be called pwm-vt8500. +config PWM_BCM2835 + tristate "BCM2835 PWM support" + help + Generic PWM framework driver for bcm2835 found on the Rasperry PI + + To compile this driver as a module, choose M here: the module will be + called pwm-bcm2835 + endif diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile index 77a8c18..0cf8d4d 100644 --- a/drivers/pwm/Makefile +++ b/drivers/pwm/Makefile @@ -20,3 +20,4 @@ obj-$(CONFIG_PWM_TIPWMSS) += pwm-tipwmss.o obj-$(CONFIG_PWM_TWL) += pwm-twl.o obj-$(CONFIG_PWM_TWL_LED) += pwm-twl-led.o obj-$(CONFIG_PWM_VT8500) += pwm-vt8500.o +obj-$(CONFIG_PWM_BCM2835) += pwm-bcm2835.o diff --git a/drivers/pwm/pwm-bcm2835.c b/drivers/pwm/pwm-bcm2835.c new file mode 100644 index 0000000..8a64666 --- /dev/null +++ b/drivers/pwm/pwm-bcm2835.c @@ -0,0 +1,275 @@ +/* + * BCM2835 PWM driver + * + * Derived from the Tegra PWM driver by NVIDIA Corporation. + * + * This software is licensed under the terms of the GNU General Public + * License version 2, as published by the Free Software Foundation, and + * may be copied, distributed, and modified under those terms. + * + * 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 <linux/clk.h> +#include <linux/err.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/of.h> +#include <linux/pwm.h> + +#define NPWM 2 + +/* Address Mappings (offsets) from Broadcom BCM2835 ARM Periperals Manual + * Section 9.6 Page 141ff + */ +#define BCM2835_PWM_CTL 0x00 /* Control register */ +#define BCM2835_PWM_STA 0x04 /* Status register */ +#define BCM2835_PWM_DMAC 0x08 /* PWM DMA Configuration */ +#define BCM2835_PWM_RNG1 0x10 /* PWM Channel 1 Range */ +#define BCM2835_PWM_DAT1 0x14 /* PWM Channel 1 Data */ +#define BCM2835_PWM_FIF1 0x18 /* PWM FIFO Input */ +#define BCM2835_PWM_RNG2 0x20 /* PWM Channel 2 Range */ +#define BCM2835_PWM_DAT2 0x24 /* PWM Channel 2 Data */ + +/* Control registers 0 and 1 are mirrored on a distance of 4 bits */ +#define HWPWM(x) ((x) << 4) + +/* TODO: We only need this register set once and use HWPWM macro to + * access 2nd output + */ +/* Control Register Bits */ +#define BCM2835_PWM_CTL_PWEN1 BIT(0) /* Channel 1 enable (RW) */ +#define BCM2835_PWM_CTL_MODE1 BIT(1) /* Channel 1 mode (RW) */ +#define BCM2835_PWM_CTL_RPTL1 BIT(2) /* Channel 1 repeat last data (RW) */ +#define BCM2835_PWM_CTL_SBIT1 BIT(3) /* Channel 1 silence bit (RW) */ +#define BCM2835_PWM_CTL_POLA1 BIT(4) /* Channel 1 polarity (RW) */ +#define BCM2835_PWM_CTL_USEF1 BIT(5) /* Channel 1 use FIFO (RW) */ +#define BCM2835_PWM_CTL_CLRF1 BIT(6) /* Channel 1 clear FIFO (RO) */ +#define BCM2835_PWM_CTL_MSEN1 BIT(7) /* Channel 1 M/S enable (RW) */ +#define BCM2835_PWM_CTL_PWEN2 BIT(8) /* Channel 2 enable (RW) */ +#define BCM2835_PWM_CTL_MODE2 BIT(9) /* Channel 2 mode (RW) */ +#define BCM2835_PWM_CTL_RPTL2 BIT(10) /* Channel 2 repeat last data (RW) */ +#define BCM2835_PWM_CTL_SBIT2 BIT(11) /* Channel 2 silence bit (RW) */ +#define BCM2835_PWM_CTL_POLA2 BIT(12) /* Channel 2 polarity (RW) */ +#define BCM2835_PWM_CTL_USEF2 BIT(13) /* Channel 2 use FIFO (RW) */ +/* Bit 14 is reserved */ +#define BCM2835_PWM_MSEN2 BIT(15) /* Channel 2 M/S enable (RW) */ +/* Bits 16 - 31 are reserved */ + +/* Status Register Bits */ +#define BCM2835_PWM_STA_FULL1 BIT(0) /* FIFO full flag (RW) */ +#define BCM2835_PWM_STA_EMPT1 BIT(1) /* FIFO empty flag (RW) */ +#define BCM2835_PWM_STA_WERR1 BIT(2) /* FIFO write error flag (RW) */ +#define BCM2835_PWM_STA_RERR1 BIT(3) /* FIFO read error flag (RW) */ +#define BCM2835_PWM_STA_GAPO1 BIT(4) /* Channel 1 gap occured (RW) */ +#define BCM2835_PWM_STA_GAPO2 BIT(5) /* Channel 2 gap occured (RW) */ +#define BCM2835_PWM_STA_GAPO3 BIT(6) /* Channel 3 gap occured (RW) */ +#define BCM2835_PWM_STA_GAPO4 BIT(7) /* Channel 4 gap occured (RW) */ +#define BCM2835_PWM_STA_BERR BIT(8) /* Bus error flag (RW) */ +#define BCM2835_PWM_STA_STA1 BIT(9) /* Channel 1 state (RW) */ +#define BCM2835_PWM_STA_STA2 BIT(10) /* Channel 1 state (RW) */ +#define BCM2835_PWM_STA_STA3 BIT(11) /* Channel 1 state (RW) */ +#define BCM2835_PWM_STA_STA4 BIT(12) /* Channel 1 state (RW) */ +/* Bits 13 - 31 are reserved */ + +struct bcm2835_pwm_dev { + struct pwm_chip chip; + struct device *dev; + struct clk *clk; + void __iomem *mmio_base; +}; + +static inline struct bcm2835_pwm_dev *to_bcm(struct pwm_chip *chip) +{ + return container_of(chip, struct bcm2835_pwm_dev, chip); +} + +static inline u32 bcm2835_readl(struct bcm2835_pwm_dev *chip, + unsigned int hwpwm, unsigned int num) +{ + num <<= HWPWM(hwpwm); + return readl(chip->mmio_base + num); +} + +static inline void bcm2835_writel(struct bcm2835_pwm_dev *chip, + unsigned int hwpwm, unsigned int num, + unsigned long val) +{ + num <<= HWPWM(hwpwm); + writel(val, chip->mmio_base + num); +} + +static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, + int duty_ns, int period_ns) +{ + struct bcm2835_pwm_dev *bcm = to_bcm(chip); + + if (WARN_ON(!bcm)) + return -ENODEV; + + if (duty_ns < 1) { + dev_err(bcm->dev, "duty is out of range: %d < 1\n", duty_ns); + return -ERANGE; + } + + if (period_ns < 1) { + dev_err(bcm->dev, "period is out of range: %d < 1\n", + period_ns); + return -ERANGE; + } + + /* disable PWM */ + bcm2835_writel(bcm, pwm->hwpwm, BCM2835_PWM_CTL, 0); + + /* write period */ + bcm2835_writel(bcm, pwm->hwpwm, BCM2835_PWM_RNG1, period_ns); + + /* write duty */ + bcm2835_writel(bcm, pwm->hwpwm, BCM2835_PWM_DAT1, duty_ns); + + /* start PWM */ + bcm2835_writel(bcm, pwm->hwpwm, BCM2835_PWM_CTL, BCM2835_PWM_CTL_PWEN1); + + return 0; +} + +static int bcm2835_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct bcm2835_pwm_dev *bcm = to_bcm(chip); + int rc = 0; + u32 val; + + if (WARN_ON(!bcm)) + return -ENODEV; + + rc = clk_prepare_enable(bcm->clk); + if (rc < 0) + return rc; + + val = bcm2835_readl(bcm, pwm->hwpwm, BCM2835_PWM_CTL); + val |= BCM2835_PWM_CTL_PWEN1; + bcm2835_writel(bcm, pwm->hwpwm, BCM2835_PWM_CTL, val); + + return 0; +} + +static void bcm2835_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct bcm2835_pwm_dev *bcm = to_bcm(chip); + u32 val; + + if (WARN_ON(!bcm)) + return; + + val = bcm2835_readl(bcm, pwm->hwpwm, BCM2835_PWM_CTL); + val &= ~BCM2835_PWM_CTL_PWEN1; + bcm2835_writel(bcm, pwm->hwpwm, BCM2835_PWM_CTL, val); + + clk_disable_unprepare(bcm->clk); +} + +static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, + enum pwm_polarity polarity) +{ + struct bcm2835_pwm_dev *bcm = to_bcm(chip); + u32 val; + + if (WARN_ON(!bcm)) + return -ENODEV; + + val = bcm2835_readl(bcm, pwm->hwpwm, BCM2835_PWM_CTL); + + if (polarity == PWM_POLARITY_NORMAL) + val |= BCM2835_PWM_CTL_POLA1; + else + val &= ~BCM2835_PWM_CTL_POLA1; + + return 0; +} + +static const struct pwm_ops bcm2835_pwm_ops = { + .config = bcm2835_pwm_config, + .enable = bcm2835_pwm_enable, + .disable = bcm2835_pwm_disable, + .set_polarity = bcm2835_set_polarity, +}; + +static int bcm2835_pwm_probe(struct platform_device *pdev) +{ + struct bcm2835_pwm_dev *bcm; + struct resource *r; + int ret; + + bcm = devm_kzalloc(&pdev->dev, sizeof(*bcm), GFP_KERNEL); + if (!bcm) + return -ENOMEM; + + r = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (!r) { + dev_err(&pdev->dev, "no memory resource defined\n"); + return -ENODEV; + } + + bcm->mmio_base = devm_ioremap_resource(&pdev->dev, r); + if (IS_ERR(bcm->mmio_base)) + return PTR_ERR(bcm->mmio_base); + + bcm->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(bcm->clk)) + return PTR_ERR(bcm->clk); + + clk_prepare_enable(bcm->clk); + + bcm->chip.ops = &bcm2835_pwm_ops; + bcm->chip.dev = &pdev->dev; + bcm->chip.base = -1; + bcm->chip.npwm = NPWM; + + ret = pwmchip_add(&bcm->chip); + if (ret < 0) + return ret; + + platform_set_drvdata(pdev, bcm); + + return 0; +} + +static int bcm2835_pwm_remove(struct platform_device *pdev) +{ + struct bcm2835_pwm_dev *bcm = platform_get_drvdata(pdev); + + if (WARN_ON(!bcm)) + return -ENODEV; + + clk_disable_unprepare(bcm->clk); + + return pwmchip_remove(&bcm->chip); +} + +static const struct of_device_id bcm2835_pwm_of_match[] = { + { .compatible = "brcm,bcm2835-pwm" }, + {}, +}; + +MODULE_DEVICE_TABLE(of, bcm2835_pwm_of_match); + +static struct platform_driver bcm2835_pwm_driver = { + .probe = bcm2835_pwm_probe, + .remove = bcm2835_pwm_remove, + .driver = { + .name = "pwm-bcm2835", + .owner = THIS_MODULE, + .of_match_table = bcm2835_pwm_of_match, + }, +}; + +module_platform_driver(bcm2835_pwm_driver); + +MODULE_AUTHOR("Johannes Thumshirn <morbid...@gmail.com>"); +MODULE_DESCRIPTION("BCM2835 PWM driver"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:pwm-bcm2835"); -- 1.8.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/