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Subject[PATCH v2 2/2] pwm: sprd: Add Spreadtrum PWM support
Date
This patch adds the Spreadtrum PWM support, which provides maximum 4
channels.

Signed-off-by: Neo Hou <neo.hou@unisoc.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
---
Changes from v1:
- Add depending on HAS_IOMEM.
- Rename parameters' names.
- Implement .apply() instead of .config(), .enable() and .disable().
- Use NSEC_PER_SEC instead of 1000000000ULL.
- Add some comments to make code more readable.
- Remove some redundant operation.
- Use standard clock properties to set clock parent.
- Other coding style optimization.
---
drivers/pwm/Kconfig | 11 ++
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-sprd.c | 307 ++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 319 insertions(+)
create mode 100644 drivers/pwm/pwm-sprd.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index a7e5751..31dfc88 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -423,6 +423,17 @@ config PWM_SPEAR
To compile this driver as a module, choose M here: the module
will be called pwm-spear.

+config PWM_SPRD
+ tristate "Spreadtrum PWM support"
+ depends on ARCH_SPRD || COMPILE_TEST
+ depends on HAS_IOMEM
+ help
+ Generic PWM framework driver for the PWM controller on
+ Spreadtrum SoCs.
+
+ To compile this driver as a module, choose M here: the module
+ will be called pwm-sprd.
+
config PWM_STI
tristate "STiH4xx PWM support"
depends on ARCH_STI
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 76b555b..26326ad 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -41,6 +41,7 @@ obj-$(CONFIG_PWM_ROCKCHIP) += pwm-rockchip.o
obj-$(CONFIG_PWM_SAMSUNG) += pwm-samsung.o
obj-$(CONFIG_PWM_SIFIVE) += pwm-sifive.o
obj-$(CONFIG_PWM_SPEAR) += pwm-spear.o
+obj-$(CONFIG_PWM_SPRD) += pwm-sprd.o
obj-$(CONFIG_PWM_STI) += pwm-sti.o
obj-$(CONFIG_PWM_STM32) += pwm-stm32.o
obj-$(CONFIG_PWM_STM32_LP) += pwm-stm32-lp.o
diff --git a/drivers/pwm/pwm-sprd.c b/drivers/pwm/pwm-sprd.c
new file mode 100644
index 0000000..067e711
--- /dev/null
+++ b/drivers/pwm/pwm-sprd.c
@@ -0,0 +1,307 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Spreadtrum Communications Inc.
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+
+#define SPRD_PWM_PRESCALE 0x0
+#define SPRD_PWM_MOD 0x4
+#define SPRD_PWM_DUTY 0x8
+#define SPRD_PWM_ENABLE 0x18
+
+#define SPRD_PWM_MOD_MAX GENMASK(7, 0)
+#define SPRD_PWM_DUTY_MSK GENMASK(15, 0)
+#define SPRD_PWM_PRESCALE_MSK GENMASK(7, 0)
+#define SPRD_PWM_ENABLE_BIT BIT(0)
+
+#define SPRD_PWM_NUM 4
+#define SPRD_PWM_REGS_SHIFT 5
+#define SPRD_PWM_NUM_CLKS 2
+#define SPRD_PWM_OUTPUT_CLK 1
+
+struct sprd_pwm_chn {
+ struct clk_bulk_data clks[SPRD_PWM_NUM_CLKS];
+ u32 clk_rate;
+};
+
+struct sprd_pwm_chip {
+ void __iomem *base;
+ struct device *dev;
+ struct pwm_chip chip;
+ int num_pwms;
+ struct sprd_pwm_chn chn[SPRD_PWM_NUM];
+};
+
+/*
+ * The list of clocks required by PWM channels, and each channel has 2 clocks:
+ * enable clock and pwm clock.
+ */
+static const char * const sprd_pwm_clks[] = {
+ "enable0", "pwm0",
+ "enable1", "pwm1",
+ "enable2", "pwm2",
+ "enable3", "pwm3",
+};
+
+static u32 sprd_pwm_read(struct sprd_pwm_chip *spc, u32 hwid, u32 reg)
+{
+ u32 offset = reg + (hwid << SPRD_PWM_REGS_SHIFT);
+
+ return readl_relaxed(spc->base + offset);
+}
+
+static void sprd_pwm_write(struct sprd_pwm_chip *spc, u32 hwid,
+ u32 reg, u32 val)
+{
+ u32 offset = reg + (hwid << SPRD_PWM_REGS_SHIFT);
+
+ writel_relaxed(val, spc->base + offset);
+}
+
+static void sprd_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+ struct pwm_state *state)
+{
+ struct sprd_pwm_chip *spc =
+ container_of(chip, struct sprd_pwm_chip, chip);
+ struct sprd_pwm_chn *chn = &spc->chn[pwm->hwpwm];
+ u32 val, duty, prescale;
+ u64 tmp;
+ int ret;
+
+ /*
+ * The clocks to PWM channel has to be enabled first before
+ * reading to the registers.
+ */
+ ret = clk_bulk_prepare_enable(SPRD_PWM_NUM_CLKS, chn->clks);
+ if (ret) {
+ dev_err(spc->dev, "failed to enable pwm%u clocks\n",
+ pwm->hwpwm);
+ return;
+ }
+
+ val = sprd_pwm_read(spc, pwm->hwpwm, SPRD_PWM_ENABLE);
+ if (val & SPRD_PWM_ENABLE_BIT)
+ state->enabled = true;
+ else
+ state->enabled = false;
+
+ /*
+ * The hardware provides a counter that is feed by the source clock.
+ * The period length is (PRESCALE + 1) * MOD counter steps.
+ * The duty cycle length is (PRESCALE + 1) * DUTY counter steps.
+ * Thus the period_ns and duty_ns calculation formula should be:
+ * period_ns = NSEC_PER_SEC * (prescale + 1) * mod / clk_rate
+ * duty_ns = NSEC_PER_SEC * (prescale + 1) * duty / clk_rate
+ */
+ val = sprd_pwm_read(spc, pwm->hwpwm, SPRD_PWM_PRESCALE);
+ prescale = val & SPRD_PWM_PRESCALE_MSK;
+ tmp = (prescale + 1) * NSEC_PER_SEC * SPRD_PWM_MOD_MAX;
+ state->period = DIV_ROUND_CLOSEST_ULL(tmp, chn->clk_rate);
+
+ val = sprd_pwm_read(spc, pwm->hwpwm, SPRD_PWM_DUTY);
+ duty = val & SPRD_PWM_DUTY_MSK;
+ tmp = (prescale + 1) * NSEC_PER_SEC * duty;
+ state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, chn->clk_rate);
+
+ /* Disable PWM clocks if the PWM channel is not in enable state. */
+ if (!state->enabled)
+ clk_bulk_disable_unprepare(SPRD_PWM_NUM_CLKS, chn->clks);
+}
+
+static int sprd_pwm_config(struct sprd_pwm_chip *spc, struct pwm_device *pwm,
+ int duty_ns, int period_ns)
+{
+ struct sprd_pwm_chn *chn = &spc->chn[pwm->hwpwm];
+ u64 div, tmp;
+ u32 prescale, duty;
+
+ /*
+ * The hardware provides a counter that is feed by the source clock.
+ * The period length is (PRESCALE + 1) * MOD counter steps.
+ * The duty cycle length is (PRESCALE + 1) * DUTY counter steps.
+ *
+ * To keep the maths simple we're always using MOD = SPRD_PWM_MOD_MAX.
+ * The value for PRESCALE is selected such that the resulting period
+ * gets the maximal length not bigger than the requested one with the
+ * given settings (MOD = SPRD_PWM_MOD_MAX and input clock).
+ */
+ duty = duty_ns * SPRD_PWM_MOD_MAX / period_ns;
+
+ tmp = (u64)chn->clk_rate * period_ns;
+ div = NSEC_PER_SEC * SPRD_PWM_MOD_MAX;
+ prescale = div64_u64(tmp, div) - 1;
+ if (prescale > SPRD_PWM_PRESCALE_MSK)
+ prescale = SPRD_PWM_PRESCALE_MSK;
+
+ /*
+ * Note: The MOD must be configured before DUTY, and the hardware can
+ * ensure current running period is completed before changing a new
+ * configuration to avoid mixed settings.
+ */
+ sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_MOD, SPRD_PWM_MOD_MAX);
+ sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_DUTY, duty);
+ sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_PRESCALE, prescale);
+
+ return 0;
+}
+
+static int sprd_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+ struct pwm_state *state)
+{
+ struct sprd_pwm_chip *spc =
+ container_of(chip, struct sprd_pwm_chip, chip);
+ struct sprd_pwm_chn *chn = &spc->chn[pwm->hwpwm];
+ struct pwm_state cstate;
+ int ret;
+
+ pwm_get_state(pwm, &cstate);
+
+ if (state->enabled) {
+ if (!cstate.enabled) {
+ /*
+ * The clocks to PWM channel has to be enabled first
+ * before writing to the registers.
+ */
+ ret = clk_bulk_prepare_enable(SPRD_PWM_NUM_CLKS,
+ chn->clks);
+ if (ret) {
+ dev_err(spc->dev,
+ "failed to enable pwm%u clocks\n",
+ pwm->hwpwm);
+ return ret;
+ }
+ }
+
+ if (state->period != cstate.period ||
+ state->duty_cycle != cstate.duty_cycle) {
+ ret = sprd_pwm_config(spc, pwm, state->duty_cycle,
+ state->period);
+ if (ret)
+ return ret;
+ }
+
+ sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_ENABLE, 1);
+ } else if (cstate.enabled) {
+ sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_ENABLE, 0);
+
+ clk_bulk_disable_unprepare(SPRD_PWM_NUM_CLKS, chn->clks);
+ }
+
+ return 0;
+}
+
+static const struct pwm_ops sprd_pwm_ops = {
+ .apply = sprd_pwm_apply,
+ .get_state = sprd_pwm_get_state,
+ .owner = THIS_MODULE,
+};
+
+static int sprd_pwm_clk_init(struct sprd_pwm_chip *spc)
+{
+ struct clk *clk_pwm;
+ int ret, i, clk_index = 0;
+
+ for (i = 0; i < SPRD_PWM_NUM; i++) {
+ struct sprd_pwm_chn *chn = &spc->chn[i];
+ int j;
+
+ for (j = 0; j < SPRD_PWM_NUM_CLKS; ++j)
+ chn->clks[j].id = sprd_pwm_clks[clk_index++];
+
+ ret = devm_clk_bulk_get(spc->dev, SPRD_PWM_NUM_CLKS, chn->clks);
+ if (ret) {
+ if (ret == -ENOENT)
+ break;
+
+ dev_err(spc->dev, "failed to get channel clocks\n");
+ return ret;
+ }
+
+ clk_pwm = chn->clks[SPRD_PWM_OUTPUT_CLK].clk;
+ chn->clk_rate = clk_get_rate(clk_pwm);
+ }
+
+ if (!i) {
+ dev_err(spc->dev, "no available PWM channels\n");
+ return -EINVAL;
+ }
+
+ spc->num_pwms = i;
+
+ return 0;
+}
+
+static int sprd_pwm_probe(struct platform_device *pdev)
+{
+ struct sprd_pwm_chip *spc;
+ int ret;
+
+ spc = devm_kzalloc(&pdev->dev, sizeof(*spc), GFP_KERNEL);
+ if (!spc)
+ return -ENOMEM;
+
+ spc->base = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(spc->base))
+ return PTR_ERR(spc->base);
+
+ spc->dev = &pdev->dev;
+ platform_set_drvdata(pdev, spc);
+
+ ret = sprd_pwm_clk_init(spc);
+ if (ret)
+ return ret;
+
+ spc->chip.dev = &pdev->dev;
+ spc->chip.ops = &sprd_pwm_ops;
+ spc->chip.base = -1;
+ spc->chip.npwm = spc->num_pwms;
+
+ ret = pwmchip_add(&spc->chip);
+ if (ret)
+ dev_err(&pdev->dev, "failed to add PWM chip\n");
+
+ return ret;
+}
+
+static int sprd_pwm_remove(struct platform_device *pdev)
+{
+ struct sprd_pwm_chip *spc = platform_get_drvdata(pdev);
+ int ret, i;
+
+ ret = pwmchip_remove(&spc->chip);
+
+ for (i = 0; i < spc->num_pwms; i++) {
+ struct sprd_pwm_chn *chn = &spc->chn[i];
+
+ clk_bulk_disable_unprepare(SPRD_PWM_NUM_CLKS, chn->clks);
+ }
+
+ return ret;
+}
+
+static const struct of_device_id sprd_pwm_of_match[] = {
+ { .compatible = "sprd,ums512-pwm", },
+ { },
+};
+MODULE_DEVICE_TABLE(of, sprd_pwm_of_match);
+
+static struct platform_driver sprd_pwm_driver = {
+ .driver = {
+ .name = "sprd-pwm",
+ .of_match_table = sprd_pwm_of_match,
+ },
+ .probe = sprd_pwm_probe,
+ .remove = sprd_pwm_remove,
+};
+
+module_platform_driver(sprd_pwm_driver);
+
+MODULE_DESCRIPTION("Spreadtrum PWM Driver");
+MODULE_LICENSE("GPL v2");
--
1.7.9.5
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