[PATCH v6 2/5] pwm: kona: Introduce Kona PWM controller support

From: Tim Kryger
Date: Fri Apr 18 2014 - 12:46:34 EST

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Add support for the six-channel Kona PWM controller found on Broadcom
mobile SoCs like bcm281xx.

Signed-off-by: Tim Kryger <tim.kryger@xxxxxxxxxx>
Reviewed-by: Alex Elder <elder@xxxxxxxxxx>
Reviewed-by: Markus Mayer <markus.mayer@xxxxxxxxxx>
---
drivers/pwm/Kconfig | 9 ++
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-bcm-kona.c | 319 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 329 insertions(+)
create mode 100644 drivers/pwm/pwm-bcm-kona.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 5b34ff2..4ad7b89 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_BCM_KONA
+ tristate "Kona PWM support"
+ depends on ARCH_BCM_MOBILE
+ help
+ Generic PWM framework driver for Broadcom Kona PWM block.
+
+ To compile this driver as a module, choose M here: the module
+ will be called pwm-bcm-kona.
+
config PWM_BFIN
tristate "Blackfin PWM support"
depends on BFIN_GPTIMERS
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index e57d2c3..5c86a19 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-$(CONFIG_PWM_BCM_KONA) += pwm-bcm-kona.o
obj-$(CONFIG_PWM_BFIN) += pwm-bfin.o
obj-$(CONFIG_PWM_CLPS711X) += pwm-clps711x.o
obj-$(CONFIG_PWM_EP93XX) += pwm-ep93xx.o
diff --git a/drivers/pwm/pwm-bcm-kona.c b/drivers/pwm/pwm-bcm-kona.c
new file mode 100644
index 0000000..ee8a59d
--- /dev/null
+++ b/drivers/pwm/pwm-bcm-kona.c
@@ -0,0 +1,319 @@
+/*
+ * Copyright (C) 2014 Broadcom Corporation
+ *
+ * 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/ioport.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+/*
+ * The Kona PWM has some unusual characteristics. Here are the main points.
+ *
+ * 1) There is no disable bit and the hardware docs advise programming a zero
+ * duty to achieve output equivalent to that of a normal disable operation.
+ *
+ * 2) Changes to prescale, duty, period, and polarity do not take effect until
+ * a subsequent rising edge of the trigger bit.
+ *
+ * 3) If the smooth bit and trigger bit are both low, the output is a constant
+ * high signal. Otherwise, the earlier waveform continues to be output.
+ *
+ * 4) If the smooth bit is set on the rising edge of the trigger bit, output
+ * will transition to the new settings on a period boundary (which could be
+ * seconds away). If the smooth bit is clear, new settings will be applied
+ * as soon as possible (the hardware always has a 400ns delay).
+ *
+ * 5) When the external clock that feeds the PWM is disabled, output is pegged
+ * high or low depending on its state at that exact instant.
+ */
+
+#define PWM_CONTROL_OFFSET (0x00000000)
+#define PWM_CONTROL_SMOOTH_SHIFT(chan) (24 + (chan))
+#define PWM_CONTROL_TYPE_SHIFT(chan) (16 + (chan))
+#define PWM_CONTROL_POLARITY_SHIFT(chan) (8 + (chan))
+#define PWM_CONTROL_TRIGGER_SHIFT(chan) (chan)
+
+#define PRESCALE_OFFSET (0x00000004)
+#define PRESCALE_SHIFT(chan) ((chan) << 2)
+#define PRESCALE_MASK(chan) (0x7 << PRESCALE_SHIFT(chan))
+#define PRESCALE_MIN (0x00000000)
+#define PRESCALE_MAX (0x00000007)
+
+#define PERIOD_COUNT_OFFSET(chan) (0x00000008 + ((chan) << 3))
+#define PERIOD_COUNT_MIN (0x00000002)
+#define PERIOD_COUNT_MAX (0x00ffffff)
+
+#define DUTY_CYCLE_HIGH_OFFSET(chan) (0x0000000c + ((chan) << 3))
+#define DUTY_CYCLE_HIGH_MIN (0x00000000)
+#define DUTY_CYCLE_HIGH_MAX (0x00ffffff)
+
+struct kona_pwmc {
+ struct pwm_chip chip;
+ void __iomem *base;
+ struct clk *clk;
+};
+
+static inline struct kona_pwmc *to_kona_pwmc(struct pwm_chip *_chip)
+{
+ return container_of(_chip, struct kona_pwmc, chip);
+}
+
+static void kona_pwmc_apply_settings(struct kona_pwmc *kp, unsigned int chan)
+{
+ unsigned int value = readl(kp->base + PWM_CONTROL_OFFSET);
+
+ /* Clear trigger bit but set smooth bit to maintain old output */
+ value |= 1 << PWM_CONTROL_SMOOTH_SHIFT(chan);
+ value &= ~(1 << PWM_CONTROL_TRIGGER_SHIFT(chan));
+ writel(value, kp->base + PWM_CONTROL_OFFSET);
+
+ /* Set trigger bit and clear smooth bit to apply new settings */
+ value &= ~(1 << PWM_CONTROL_SMOOTH_SHIFT(chan));
+ value |= 1 << PWM_CONTROL_TRIGGER_SHIFT(chan);
+ writel(value, kp->base + PWM_CONTROL_OFFSET);
+}
+
+static int kona_pwmc_config(struct pwm_chip *chip, struct pwm_device *pwm,
+ int duty_ns, int period_ns)
+{
+ struct kona_pwmc *kp = to_kona_pwmc(chip);
+ u64 val, div, rate;
+ unsigned long prescale = PRESCALE_MIN, pc, dc;
+ unsigned int value, chan = pwm->hwpwm;
+
+ /*
+ * 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))
+ */
+
+ rate = clk_get_rate(kp->clk);
+
+ while (1) {
+ div = 1000000000;
+ div *= 1 + prescale;
+ val = rate * period_ns;
+ pc = div64_u64(val, div);
+ val = rate * duty_ns;
+ dc = div64_u64(val, div);
+
+ /* If duty_ns or period_ns are not achievable then return */
+ if (pc < PERIOD_COUNT_MIN || dc < DUTY_CYCLE_HIGH_MIN)
+ return -EINVAL;
+
+ /* If pc and dc are in bounds, the calculation is done */
+ if (pc <= PERIOD_COUNT_MAX && dc <= DUTY_CYCLE_HIGH_MAX)
+ break;
+
+ /* Otherwise, increase prescale and recalculate pc and dc */
+ if (++prescale > PRESCALE_MAX)
+ return -EINVAL;
+ }
+
+ /* If the PWM channel is enabled, write the settings to the HW */
+ if (test_bit(PWMF_ENABLED, &pwm->flags)) {
+ value = readl(kp->base + PRESCALE_OFFSET);
+ value &= ~PRESCALE_MASK(chan);
+ value |= prescale << PRESCALE_SHIFT(chan);
+ writel(value, kp->base + PRESCALE_OFFSET);
+
+ writel(pc, kp->base + PERIOD_COUNT_OFFSET(chan));
+
+ writel(dc, kp->base + DUTY_CYCLE_HIGH_OFFSET(chan));
+
+ kona_pwmc_apply_settings(kp, chan);
+ }
+
+ return 0;
+}
+
+static int kona_pwmc_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
+ enum pwm_polarity polarity)
+{
+ struct kona_pwmc *kp = to_kona_pwmc(chip);
+ unsigned int chan = pwm->hwpwm;
+ unsigned int value;
+ int ret;
+
+ ret = clk_prepare_enable(kp->clk);
+
+ if (ret < 0) {
+ dev_err(chip->dev, "failed to enable clock: %d\n", ret);
+ return ret;
+ }
+
+ value = readl(kp->base + PWM_CONTROL_OFFSET);
+
+ if (polarity == PWM_POLARITY_NORMAL)
+ value |= 1 << PWM_CONTROL_POLARITY_SHIFT(chan);
+ else
+ value &= ~(1 << PWM_CONTROL_POLARITY_SHIFT(chan));
+
+ writel(value, kp->base + PWM_CONTROL_OFFSET);
+
+ kona_pwmc_apply_settings(kp, chan);
+
+ /* Wait for waveform to settle before gating off the clock */
+ ndelay(400);
+
+ clk_disable_unprepare(kp->clk);
+
+ return 0;
+}
+
+static int kona_pwmc_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct kona_pwmc *kp = to_kona_pwmc(chip);
+ int ret;
+
+ ret = clk_prepare_enable(kp->clk);
+ if (ret < 0) {
+ dev_err(chip->dev, "failed to enable clock: %d\n", ret);
+ return ret;
+ }
+
+ ret = kona_pwmc_config(chip, pwm, pwm->duty_cycle, pwm->period);
+ if (ret < 0) {
+ clk_disable_unprepare(kp->clk);
+ return ret;
+ }
+
+ return 0;
+}
+
+static void kona_pwmc_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct kona_pwmc *kp = to_kona_pwmc(chip);
+ unsigned int chan = pwm->hwpwm;
+
+ /* Simulate a disable by configuring for zero duty */
+ writel(0, kp->base + DUTY_CYCLE_HIGH_OFFSET(chan));
+ kona_pwmc_apply_settings(kp, chan);
+
+ /* Wait for waveform to settle before gating off the clock */
+ ndelay(400);
+
+ clk_disable_unprepare(kp->clk);
+}
+
+static const struct pwm_ops kona_pwm_ops = {
+ .config = kona_pwmc_config,
+ .set_polarity = kona_pwmc_set_polarity,
+ .enable = kona_pwmc_enable,
+ .disable = kona_pwmc_disable,
+ .owner = THIS_MODULE,
+};
+
+static int kona_pwmc_probe(struct platform_device *pdev)
+{
+ struct kona_pwmc *kp;
+ struct resource *res;
+ unsigned int chan;
+ unsigned int value = 0;
+ int ret = 0;
+
+ kp = devm_kzalloc(&pdev->dev, sizeof(*kp), GFP_KERNEL);
+ if (kp == NULL)
+ return -ENOMEM;
+
+ platform_set_drvdata(pdev, kp);
+
+ kp->chip.dev = &pdev->dev;
+ kp->chip.ops = &kona_pwm_ops;
+ kp->chip.base = -1;
+ kp->chip.npwm = 6;
+ kp->chip.of_xlate = of_pwm_xlate_with_flags;
+ kp->chip.of_pwm_n_cells = 3;
+ kp->chip.can_sleep = true;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ kp->base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(kp->base))
+ return PTR_ERR(kp->base);
+
+ kp->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(kp->clk)) {
+ dev_err(&pdev->dev, "failed to get clock: %ld\n",
+ PTR_ERR(kp->clk));
+ return PTR_ERR(kp->clk);
+ }
+
+ ret = clk_prepare_enable(kp->clk);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to enable clock: %d\n", ret);
+ return ret;
+ }
+
+ /* Set smooth mode, push/pull, and normal polarity for all channels */
+ for (chan = 0; chan < kp->chip.npwm; chan++) {
+ value |= (1 << PWM_CONTROL_SMOOTH_SHIFT(chan));
+ value |= (1 << PWM_CONTROL_TYPE_SHIFT(chan));
+ value |= (1 << PWM_CONTROL_POLARITY_SHIFT(chan));
+ }
+
+ writel(value, kp->base + PWM_CONTROL_OFFSET);
+
+ clk_disable_unprepare(kp->clk);
+
+ ret = pwmchip_add(&kp->chip);
+ if (ret < 0)
+ dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
+
+ return ret;
+}
+
+static int kona_pwmc_remove(struct platform_device *pdev)
+{
+ struct kona_pwmc *kp = platform_get_drvdata(pdev);
+ unsigned int chan;
+
+ for (chan = 0; chan < kp->chip.npwm; chan++)
+ if (test_bit(PWMF_ENABLED, &kp->chip.pwms[chan].flags))
+ clk_disable_unprepare(kp->clk);
+
+ return pwmchip_remove(&kp->chip);
+}
+
+static const struct of_device_id bcm_kona_pwmc_dt[] = {
+ { .compatible = "brcm,kona-pwm" },
+ { },
+};
+MODULE_DEVICE_TABLE(of, bcm_kona_pwmc_dt);
+
+static struct platform_driver kona_pwmc_driver = {
+ .driver = {
+ .name = "bcm-kona-pwm",
+ .of_match_table = bcm_kona_pwmc_dt,
+ },
+ .probe = kona_pwmc_probe,
+ .remove = kona_pwmc_remove,
+};
+
+module_platform_driver(kona_pwmc_driver);
+MODULE_AUTHOR("Broadcom Corporation <bcm-kernel-feedback-list@xxxxxxxxxxxx>");
+MODULE_AUTHOR("Tim Kryger <tkryger@xxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Broadcom Kona PWM driver");
+MODULE_LICENSE("GPL v2");
--
1.7.9.5

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Next message: Tim Kryger: "[PATCH v6 0/5] Add Broadcom Kona PWM Support"
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