[PATCH v4 2/3] pwm: iproc: Add support for Broadcom iproc pwm controller

Yendapally Reddy Dhananjaya Reddy
2016-06-22T11:31:16Z

Add support for the PWM controller present in Broadcom's iProc
family of SoCs. This driver is derived from the pwm-bcm-kona
driver, with changes to the register offsets and bit positions.
It has been tested on the Northstar+ bcm958625HR board.

Signed-off-by: Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com>
---
drivers/pwm/Kconfig | 10 ++
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-bcm-iproc.c | 327 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 338 insertions(+)
create mode 100644 drivers/pwm/pwm-bcm-iproc.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index c182efc..1339b62 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -74,6 +74,16 @@ config PWM_ATMEL_TCB
To compile this driver as a module, choose M here: the module
will be called pwm-atmel-tcb.

+config PWM_BCM_IPROC
+ tristate "iProc PWM support"
+ depends on ARCH_BCM_IPROC || COMPILE_TEST
+ help
+ Generic PWM framework driver for Broadcom iProc PWM block. This
+ block is used in Broadcom iProc SoC's.
+
+ To compile this driver as a module, choose M here: the module
+ will be called pwm-bcm-iproc.
+
config PWM_BCM_KONA
tristate "Kona PWM support"
depends on ARCH_BCM_MOBILE
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index dd35bc1..a196d79 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -4,6 +4,7 @@ obj-$(CONFIG_PWM_AB8500) += pwm-ab8500.o
obj-$(CONFIG_PWM_ATMEL) += pwm-atmel.o
obj-$(CONFIG_PWM_ATMEL_HLCDC_PWM) += pwm-atmel-hlcdc.o
obj-$(CONFIG_PWM_ATMEL_TCB) += pwm-atmel-tcb.o
+obj-$(CONFIG_PWM_BCM_IPROC) += pwm-bcm-iproc.o
obj-$(CONFIG_PWM_BCM_KONA) += pwm-bcm-kona.o
obj-$(CONFIG_PWM_BCM2835) += pwm-bcm2835.o
obj-$(CONFIG_PWM_BERLIN) += pwm-berlin.o
diff --git a/drivers/pwm/pwm-bcm-iproc.c b/drivers/pwm/pwm-bcm-iproc.c
new file mode 100644
index 0000000..952c457
--- /dev/null
+++ b/drivers/pwm/pwm-bcm-iproc.c
@@ -0,0 +1,327 @@
+/*
+ * Copyright (C) 2016 Broadcom
+ *
+ * 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.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; 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/delay.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+
+#define IPROC_PWM_CTRL_OFFSET (0x00)
+#define IPROC_PWM_CTRL_TYPE_SHIFT(chan) (15 + (chan))
+#define IPROC_PWM_CTRL_POLARITY_SHIFT(chan) (8 + (chan))
+#define IPROC_PWM_CTRL_EN_SHIFT(chan) (chan)
+
+#define IPROC_PWM_PERIOD_OFFSET(chan) (0x04 + ((chan) << 3))
+#define IPROC_PWM_PERIOD_MIN (0x02)
+#define IPROC_PWM_PERIOD_MAX (0xffff)
+
+#define IPROC_PWM_DUTY_CYCLE_OFFSET(chan) (0x08 + ((chan) << 3))
+#define IPROC_PWM_DUTY_CYCLE_MIN (0x00)
+#define IPROC_PWM_DUTY_CYCLE_MAX (0xffff)
+
+#define IPROC_PWM_PRESCALE_OFFSET (0x24)
+#define IPROC_PWM_PRESCALE_BITS (0x06)
+#define IPROC_PWM_PRESCALE_SHIFT(chan) ((3 - (chan)) * \
+ IPROC_PWM_PRESCALE_BITS)
+#define IPROC_PWM_PRESCALE_MASK(chan) (IPROC_PWM_PRESCALE_MAX << \
+ IPROC_PWM_PRESCALE_SHIFT(chan))
+#define IPROC_PWM_PRESCALE_MIN (0x00)
+#define IPROC_PWM_PRESCALE_MAX (0x3f)
+
+#define IPROC_PWM_CHANNEL_COUNT (0x04)
+
+struct iproc_pwmc {
+ struct pwm_chip chip;
+ void __iomem *base;
+ struct clk *clk;
+};
+
+static inline struct iproc_pwmc *to_iproc_pwmc(struct pwm_chip *_chip)
+{
+ return container_of(_chip, struct iproc_pwmc, chip);
+}
+
+static void iproc_pwmc_unset_enable_bit(struct iproc_pwmc *ip, u32 chan)
+{
+ unsigned int value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
+
+ value &= ~(1 << IPROC_PWM_CTRL_EN_SHIFT(chan));
+ writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
+
+ /*
+ * There must be a min 400ns delay between clearing trigger and setting
+ * it. Failing to do this may result in no PWM signal.
+ */
+ ndelay(400);
+}
+
+static void iproc_pwmc_set_enable_bit(struct iproc_pwmc *ip, unsigned int chan)
+{
+ unsigned int value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
+
+ /* Set trigger bit to apply new settings */
+ value |= 1 << IPROC_PWM_CTRL_EN_SHIFT(chan);
+ writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
+
+ /* Trigger bit must be held high for at least 400 ns. */
+ ndelay(400);
+}
+
+static int iproc_pwmc_config(struct pwm_chip *chip, struct pwm_device *pwm,
+ int duty_ns, int period_ns, bool config_apply)
+{
+ unsigned long prescale = IPROC_PWM_PRESCALE_MIN;
+ struct iproc_pwmc *ip = to_iproc_pwmc(chip);
+ unsigned int value, chan = pwm->hwpwm;
+ unsigned long period_cnt, duty_cnt;
+ u64 val, div, rate;
+
+ rate = clk_get_rate(ip->clk);
+ if (!rate) {
+ dev_err(pwm->chip->dev, "pwm clock has no frequency\n");
+ return -EINVAL;
+ }
+
+ /*
+ * Find period count, duty count and prescale to suit duty_ns and
+ * period_ns. This is done according to formulas described below:
+ *
+ * period_ns = 10^9 * (PRESCALE + 1) * PC / PWM_CLK_RATE
+ * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
+ *
+ * PC = (PWM_CLK_RATE * period_ns) / (10^9 * (PRESCALE + 1))
+ * DC = (PWM_CLK_RATE * duty_ns) / (10^9 * (PRESCALE + 1))
+ */
+ while (1) {
+ div = 1000000000;
+ div *= 1 + prescale;
+ val = rate * period_ns;
+ period_cnt = div64_u64(val, div);
+ val = rate * duty_ns;
+ duty_cnt = div64_u64(val, div);
+
+ if (period_cnt < IPROC_PWM_PERIOD_MIN ||
+ duty_cnt < IPROC_PWM_DUTY_CYCLE_MIN)
+ return -EINVAL;
+
+ if (period_cnt <= IPROC_PWM_PERIOD_MAX &&
+ duty_cnt <= IPROC_PWM_DUTY_CYCLE_MAX)
+ break;
+
+ /* Otherwise, increase prescale and recalculate counts */
+ if (++prescale > IPROC_PWM_PRESCALE_MAX)
+ return -EINVAL;
+ }
+
+ /*
+ * Don't apply settings if disabled. The period and duty cycle are
+ * always calculated above to ensure the new values are
+ * validated immediately instead of on enable.
+ */
+ if (pwm_is_enabled(pwm) || config_apply) {
+ iproc_pwmc_unset_enable_bit(ip, chan);
+
+ value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET);
+ value &= ~IPROC_PWM_PRESCALE_MASK(chan);
+ value |= prescale << IPROC_PWM_PRESCALE_SHIFT(chan);
+
+ writel(value, ip->base + IPROC_PWM_PRESCALE_OFFSET);
+ writel(period_cnt, ip->base + IPROC_PWM_PERIOD_OFFSET(chan));
+ writel(duty_cnt, ip->base + IPROC_PWM_DUTY_CYCLE_OFFSET(chan));
+
+ iproc_pwmc_set_enable_bit(ip, chan);
+ }
+
+ return 0;
+}
+
+static int iproc_pwmc_set_polarity(struct pwm_chip *chip,
+ struct pwm_device *pwm,
+ enum pwm_polarity polarity)
+{
+ struct iproc_pwmc *ip = to_iproc_pwmc(chip);
+ unsigned int chan = pwm->hwpwm;
+ unsigned int value;
+ int ret;
+
+ ret = clk_prepare_enable(ip->clk);
+ if (ret < 0) {
+ dev_err(chip->dev, "failed to enable clock: %d\n", ret);
+ return ret;
+ }
+
+ iproc_pwmc_unset_enable_bit(ip, chan);
+
+ value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
+ if (polarity == PWM_POLARITY_NORMAL)
+ value |= 1 << IPROC_PWM_CTRL_POLARITY_SHIFT(chan);
+ else
+ value &= ~(1 << IPROC_PWM_CTRL_POLARITY_SHIFT(chan));
+ writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
+
+ iproc_pwmc_set_enable_bit(ip, chan);
+
+ clk_disable_unprepare(ip->clk);
+
+ return 0;
+}
+
+static int iproc_pwmc_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct iproc_pwmc *ip = to_iproc_pwmc(chip);
+ int ret;
+
+ ret = clk_prepare_enable(ip->clk);
+ if (ret < 0) {
+ dev_err(chip->dev, "failed to enable clock: %d\n", ret);
+ return ret;
+ }
+
+ ret = iproc_pwmc_config(chip, pwm, pwm_get_duty_cycle(pwm),
+ pwm_get_period(pwm), true);
+ if (ret < 0) {
+ clk_disable_unprepare(ip->clk);
+ return ret;
+ }
+
+ return 0;
+}
+
+static void iproc_pwmc_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct iproc_pwmc *ip = to_iproc_pwmc(chip);
+ unsigned int chan = pwm->hwpwm;
+ unsigned int value;
+
+ iproc_pwmc_unset_enable_bit(ip, chan);
+
+ writel(0, ip->base + IPROC_PWM_DUTY_CYCLE_OFFSET(chan));
+ writel(0, ip->base + IPROC_PWM_PERIOD_OFFSET(chan));
+
+ /* Set prescale to 0 for this channel */
+ value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET);
+ value &= ~IPROC_PWM_PRESCALE_MASK(chan);
+ writel(value, ip->base + IPROC_PWM_PRESCALE_OFFSET);
+
+ iproc_pwmc_set_enable_bit(ip, chan);
+
+ clk_disable_unprepare(ip->clk);
+}
+
+static int iproc_pwmc_config_check(struct pwm_chip *chip,
+ struct pwm_device *pwm,
+ int duty_ns, int period_ns)
+{
+ return iproc_pwmc_config(chip, pwm, duty_ns, period_ns, false);
+}
+
+static const struct pwm_ops iproc_pwm_ops = {
+ .config = iproc_pwmc_config_check,
+ .set_polarity = iproc_pwmc_set_polarity,
+ .enable = iproc_pwmc_enable,
+ .disable = iproc_pwmc_disable,
+ .owner = THIS_MODULE,
+};
+
+static int iproc_pwmc_probe(struct platform_device *pdev)
+{
+ struct iproc_pwmc *ip;
+ struct resource *res;
+ unsigned int value;
+ unsigned int chan;
+ int ret;
+
+ ip = devm_kzalloc(&pdev->dev, sizeof(*ip), GFP_KERNEL);
+ if (ip == NULL)
+ return -ENOMEM;
+
+ platform_set_drvdata(pdev, ip);
+
+ ip->chip.dev = &pdev->dev;
+ ip->chip.ops = &iproc_pwm_ops;
+ ip->chip.base = -1;
+ ip->chip.npwm = IPROC_PWM_CHANNEL_COUNT;
+ ip->chip.of_xlate = of_pwm_xlate_with_flags;
+ ip->chip.of_pwm_n_cells = 3;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ ip->base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(ip->base))
+ return PTR_ERR(ip->base);
+
+ ip->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(ip->clk)) {
+ dev_err(&pdev->dev, "failed to get clock: %ld\n",
+ PTR_ERR(ip->clk));
+ return PTR_ERR(ip->clk);
+ }
+
+ ret = clk_prepare_enable(ip->clk);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to enable clock: %d\n", ret);
+ return ret;
+ }
+
+ /* Set full drive and normal polarity for all channels */
+ value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
+ for (chan = 0; chan < ip->chip.npwm; chan++) {
+ value &= ~(1 << IPROC_PWM_CTRL_TYPE_SHIFT(chan));
+ value |= 1 << IPROC_PWM_CTRL_POLARITY_SHIFT(chan);
+ }
+ writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
+
+ clk_disable_unprepare(ip->clk);
+
+ ret = pwmchip_add(&ip->chip);
+ if (ret < 0)
+ dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
+
+ return ret;
+}
+
+static int iproc_pwmc_remove(struct platform_device *pdev)
+{
+ struct iproc_pwmc *ip = platform_get_drvdata(pdev);
+ unsigned int chan;
+
+ for (chan = 0; chan < ip->chip.npwm; chan++)
+ if (pwm_is_enabled(&ip->chip.pwms[chan]))
+ clk_disable_unprepare(ip->clk);
+
+ return pwmchip_remove(&ip->chip);
+}
+
+static const struct of_device_id bcm_iproc_pwmc_dt[] = {
+ { .compatible = "brcm,iproc-pwm" },
+ { },
+};
+MODULE_DEVICE_TABLE(of, bcm_iproc_pwmc_dt);
+
+static struct platform_driver iproc_pwmc_driver = {
+ .driver = {
+ .name = "bcm-iproc-pwm",
+ .of_match_table = bcm_iproc_pwmc_dt,
+ },
+ .probe = iproc_pwmc_probe,
+ .remove = iproc_pwmc_remove,
+};
+module_platform_driver(iproc_pwmc_driver);
+
+MODULE_AUTHOR("Broadcom Corporation");
+MODULE_DESCRIPTION("Broadcom iProc PWM driver");
+MODULE_LICENSE("GPL v2");
--
2.1.0