[resend rfc v3] pwm: add BCM2835 PWM driver
Bart Tanghe
bart.tanghe at thomasmore.be
Mon Apr 28 05:54:46 PDT 2014
Add some better error handling and Device table support
Added Documentation/devicetree/bindings/pwm/pwm-bcm2835.txt
Signed-off-by: Bart Tanghe <bart.tanghe at thomasmore.be>
diff --git a/Documentation/devicetree/bindings/pwm/pwm-bcm2835.txt b/Documentation/devicetree/bindings/pwm/pwm-bcm2835.txt
new file mode 100644
index 0000000..44c0b95
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/pwm-bcm2835.txt
@@ -0,0 +1,13 @@
+bcm2835 PWM controller
+
+Required properties:
+- compatible: should be "bcrm,pwm-bcm2835"
+- reg: physical base address and length of the controller's registers
+
+Examples:
+
+pwm at 0x2020C000 {
+ compatible = "bcrm,pwm-bcm2835";
+ reg = <0x2020C000 0x28>;
+ clocks = <&clk_pwm>;
+};
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 22f2f28..20341a3 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -62,6 +62,18 @@ 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)
+ Only 1 channel is implemented.
+
+ The pwm core is tested with a pwm basic frequency of 1Mhz.
+ Use period above 1000ns
+
+ 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..ec9829b
--- /dev/null
+++ b/drivers/pwm/pwm-bcm2835.c
@@ -0,0 +1,198 @@
+/*
+ * pwm-bcm2835 driver
+ * Standard raspberry pi (gpio18 - pwm0)
+ *
+ * Copyright (C) 2014 Thomas more
+ *
+ * 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 <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+
+/*mmio regiser mapping*/
+
+#define DUTY 0x14
+#define PERIOD 0x10
+#define CHANNEL 0x10
+
+#define PWM_ENABLE 0x00000001
+#define PWM_POLARITY 0x00000010
+
+#define MASK_CTL_PWM 0x000000FF
+#define CTL_PWM 0x00000081
+
+#define DRIVER_AUTHOR "Bart Tanghe <bart.tanghe at thomasmore.be>"
+#define DRIVER_DESC "A bcm2835 pwm driver - raspberry pi development platform"
+
+struct bcm2835_pwm_chip {
+ struct pwm_chip chip;
+ struct device *dev;
+ int channel;
+ int scaler;
+ void __iomem *mmio_base;
+};
+
+static inline struct bcm2835_pwm_chip *to_bcm2835_pwm_chip(
+ struct pwm_chip *chip){
+
+ return container_of(chip, struct bcm2835_pwm_chip, chip);
+}
+
+static int bcm2835_pwm_config(struct pwm_chip *chip,
+ struct pwm_device *pwm,
+ int duty_ns, int period_ns){
+
+ struct bcm2835_pwm_chip *pc;
+
+ pc = container_of(chip, struct bcm2835_pwm_chip, chip);
+
+ iowrite32(duty_ns/pc->scaler, pc->mmio_base + DUTY);
+ iowrite32(period_ns/pc->scaler, pc->mmio_base + PERIOD);
+
+ return 0;
+}
+
+static int bcm2835_pwm_enable(struct pwm_chip *chip,
+ struct pwm_device *pwm){
+
+ struct bcm2835_pwm_chip *pc;
+
+ pc = container_of(chip, struct bcm2835_pwm_chip, chip);
+
+ iowrite32(ioread32(pc->mmio_base) | PWM_ENABLE, pc->mmio_base);
+ return 0;
+}
+
+static void bcm2835_pwm_disable(struct pwm_chip *chip,
+ struct pwm_device *pwm)
+{
+ struct bcm2835_pwm_chip *pc;
+
+ pc = to_bcm2835_pwm_chip(chip);
+
+ iowrite32(ioread32(pc->mmio_base) & ~PWM_ENABLE, pc->mmio_base);
+}
+
+static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
+ enum pwm_polarity polarity)
+{
+ struct bcm2835_pwm_chip *pc;
+
+ pc = to_bcm2835_pwm_chip(chip);
+
+ if (polarity == PWM_POLARITY_NORMAL)
+ iowrite32((ioread32(pc->mmio_base) & ~PWM_POLARITY),
+ pc->mmio_base);
+ else if (polarity == PWM_POLARITY_INVERSED)
+ iowrite32((ioread32(pc->mmio_base) | PWM_POLARITY),
+ pc->mmio_base);
+
+ 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,
+ .owner = THIS_MODULE,
+};
+
+static int bcm2835_pwm_probe(struct platform_device *pdev)
+{
+ struct bcm2835_pwm_chip *pwm;
+
+ int ret;
+ struct resource *r;
+ u32 start, end;
+ struct clk *clk;
+
+ pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
+ if (!pwm) {
+ dev_err(&pdev->dev, "failed to allocate memory\n");
+ return -ENOMEM;
+ }
+
+ pwm->dev = &pdev->dev;
+
+ clk = clk_get(&pdev->dev, NULL);
+ if (IS_ERR(clk)) {
+ dev_err(&pdev->dev, "could not find clk: %ld\n", PTR_ERR(clk));
+ devm_kfree(&pdev->dev, pwm);
+ return PTR_ERR(clk);
+ }
+
+ pwm->scaler = (int)1000000000/clk_get_rate(clk);
+
+ r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r);
+ if (IS_ERR(pwm->mmio_base)) {
+ devm_kfree(&pdev->dev, pwm);
+ return PTR_ERR(pwm->mmio_base);
+ }
+
+ start = r->start;
+ end = r->end;
+
+ pwm->chip.dev = &pdev->dev;
+ pwm->chip.ops = &bcm2835_pwm_ops;
+ pwm->chip.npwm = 2;
+
+ ret = pwmchip_add(&pwm->chip);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
+ devm_kfree(&pdev->dev, pwm);
+ return -1;
+ }
+
+ /*set the pwm0 configuration*/
+ iowrite32((ioread32(pwm->mmio_base) & ~MASK_CTL_PWM)
+ | CTL_PWM, pwm->mmio_base);
+
+ platform_set_drvdata(pdev, pwm);
+
+ return 0;
+}
+
+static int bcm2835_pwm_remove(struct platform_device *pdev)
+{
+
+ struct bcm2835_pwm_chip *pc;
+ pc = platform_get_drvdata(pdev);
+
+ if (WARN_ON(!pc))
+ return -ENODEV;
+
+ return pwmchip_remove(&pc->chip);
+}
+
+static const struct of_device_id bcm2835_pwm_of_match[] = {
+ { .compatible = "bcrm,pwm-bcm2835", },
+ { /* sentinel */ }
+};
+
+MODULE_DEVICE_TABLE(of, bcm2835_pwm_of_match);
+
+static struct platform_driver bcm2835_pwm_driver = {
+ .driver = {
+ .name = "pwm-bcm2835",
+ .owner = THIS_MODULE,
+ .of_match_table = bcm2835_pwm_of_match,
+ },
+ .probe = bcm2835_pwm_probe,
+ .remove = bcm2835_pwm_remove,
+};
+module_platform_driver(bcm2835_pwm_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
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