Add driver support for ESWIN EIC7700 PWM controller

Documentation/devicetree/bindings/pwm/eswin,eic7700-pwm.yaml new file +4 -0

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+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pwm/eswin,eic7700-pwm.yaml#

Documentation/devicetree/bindings/pwm/eswin,eic7700-pwm.yaml new file +21 -0

+  both 0% and 100% duty cycles.
+
+allOf:
+  - $ref: pwm.yaml#
+
+properties:
+  compatible:
+    const: eswin,eic7700-pwm
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  resets:
+    maxItems: 1
+
+  "#pwm-cells":
+    const: 3
+

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Documentation/devicetree/bindings/pwm/eswin,eic7700-pwm.yaml new file +4 -0

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+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pwm/eswin,eic7700-pwm.yaml#

Documentation/devicetree/bindings/pwm/eswin,eic7700-pwm.yaml line 14

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Documentation/devicetree/bindings/pwm/eswin,eic7700-pwm.yaml new file +10 -0

+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ESWIN EIC7700 PWM controller
+
+maintainers:
+  - Xiang Xu <[email protected]>
+  - Guosheng Wang <[email protected]>
+  - Xuyang Dong <[email protected]>
+
+description: |

Do not need '|' unless you need to preserve formatting.

Documentation/devicetree/bindings/pwm/eswin,eic7700-pwm.yaml line 16

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Documentation/devicetree/bindings/pwm/eswin,eic7700-pwm.yaml new file +2 -0

+  The EIC7700 PWM used the DesignWare APB timers module. The PWM driver
+  supports a duty cycle range from 0% to 100%, with explicit support for

Driver is irrelevant here. Describe hardware.

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Documentation/devicetree/bindings/pwm/eswin,eic7700-pwm.yaml new file +30 -0

+  both 0% and 100% duty cycles.
+
+allOf:
+  - $ref: pwm.yaml#
+
+properties:
+  compatible:
+    const: eswin,eic7700-pwm
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  resets:
+    maxItems: 1
+
+  "#pwm-cells":
+    const: 3
+
+  pinctrl-0: true
+  pinctrl-1: true
+
+  pinctrl-names:
+    minItems: 1
+    items:
+      - const: default
+      - const: sleep
+

Documentation/devicetree/bindings/pwm/eswin,eic7700-pwm.yaml line 47

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Documentation/devicetree/bindings/pwm/eswin,eic7700-pwm.yaml new file +1 -0

+  snps,pwm-full-range-enable:

1. Wrong vendor prefix, thats eswin, not snps.
2. Why is this a hardware property? I really do not see that. You described the desired Linux feature or behavior, not the actual hardware. The bindings are about the latter, so instead you need to rephrase the property and its description to match actual hardware capabilities/features/configuration etc.

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Documentation/devicetree/bindings/pwm/eswin,eic7700-pwm.yaml new file +10 -0

+
+  pinctrl-0: true
+  pinctrl-1: true
+
+  pinctrl-names:
+    minItems: 1
+    items:
+      - const: default
+      - const: sleep
+

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+ snps,pwm-full-range-enable:

1. Wrong vendor prefix, thats eswin, not snps.
2. Why is this a hardware property? I really do not see that. You described the desired Linux feature or behavior, not the actual hardware. The bindings are about the latter, so instead you need to rephrase the property and its description to match actual hardware capabilities/features/configuration etc.

Hi Krzysztof and Ben,

There is a patch [1] submmitted by Ben Dook a few years ago. The intention of this patch is to make DWC pwm controller can be used as platform driver. This is what we are currently working on. It seems that it would be more reasonable to continue improving this patch and make the DWC PWM driver universal, rather than creating a separate ESWIN PWM driver.

The DWC pwm 2.13a version supports "Pulse Width Modulation with 0% and 100% Duty Cycle" by programming TIMER_0N100PWM_EN bit field. We also want to support this new hardware feature. So, adding a new property, like snps,timer-0n100pwm-en, in pwm/snps,dw-apb-timers-pwm2.yaml would be better?

Krzysztof and Ben, do you think the above approach is reasonable and acceptable?

drivers/pwm/pwm-dwc-eic7700.c new file +27 -0

+#include <linux/pinctrl/consumer.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/pwm.h>
+#include <linux/reset.h>
+
+#include "pwm-dwc.h"
+
+#define DW_PWMS_TOTAL	3
+
+static int eic7700_pwm_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct dwc_pwm_drvdata *data;
+	struct pwm_chip *chip = NULL;
+	struct dwc_pwm *dwc = NULL;
+	int ret;
+
+	data = devm_kzalloc(dev, sizeof(data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	chip = dwc_pwm_alloc(dev);
+	if (IS_ERR(chip))
+		return dev_err_probe(dev, -ENOMEM, "failed to alloc pwm\n");
+
+	dwc = to_dwc_pwm(chip);

drivers/pwm/pwm-dwc-eic7700.c new file +148 -0

+	if (IS_ERR(dwc->clk))
+		return dev_err_probe(dev, PTR_ERR(dwc->clk),
+				     "failed to get clock\n");
+
+	ret = clk_prepare_enable(dwc->clk);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to enable clock\n");
+
+	dwc->rst = devm_reset_control_get_exclusive(&pdev->dev, NULL);
+	if (IS_ERR(dwc->rst)) {
+		dev_err(dev, "failed to get reset control\n");
+		ret = PTR_ERR(dwc->rst);
+		goto err_clk_disable;
+	}
+
+	ret = reset_control_deassert(dwc->rst);
+	if (ret) {
+		dev_err(dev, "failed to deassert reset: %d\n", ret);
+		goto err_clk_disable;
+	}
+
+	ret = devm_pwmchip_add(dev, chip);
+	if (ret) {
+		dev_err(dev, "failed to add pwmchip: %d\n", ret);
+		goto err_reset_assert;
+	}
+
+	data->chips[0] = chip;
+	dev_set_drvdata(dev, data);
+
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+	pm_runtime_get_noresume(dev);
+
+	return 0;
+
+err_reset_assert:
+	reset_control_assert(dwc->rst);
+err_clk_disable:
+	clk_disable_unprepare(dwc->clk);
+
+	return ret;
+}
+
+static void eic7700_pwm_remove(struct platform_device *pdev)
+{
+	struct dwc_pwm_drvdata *data = platform_get_drvdata(pdev);
+	struct pwm_chip *chip = data->chips[0];
+	struct dwc_pwm *dwc = to_dwc_pwm(chip);
+	struct device *dev = &pdev->dev;
+
+	clk_disable_unprepare(dwc->clk);
+	reset_control_assert(dwc->rst);
+
+	pm_runtime_put_sync(dev);
+	pm_runtime_disable(dev);
+}
+
+static int eic7700_pwm_runtime_suspend(struct device *dev)
+{
+	struct dwc_pwm_drvdata *data = dev_get_drvdata(dev);
+	struct pwm_chip *chip = data->chips[0];
+	struct dwc_pwm *dwc = to_dwc_pwm(chip);
+	int idx, ret;
+
+	for (idx = 0; idx < DW_PWMS_TOTAL; idx++) {
+		if (chip->pwms[idx].state.enabled)
+			return -EBUSY;
+
+		dwc->ctx[idx].cnt = dwc_pwm_readl(dwc, DWC_TIM_LD_CNT(idx));
+		dwc->ctx[idx].cnt2 = dwc_pwm_readl(dwc, DWC_TIM_LD_CNT2(idx));
+		dwc->ctx[idx].ctrl = dwc_pwm_readl(dwc, DWC_TIM_CTRL(idx));
+	}
+
+	clk_disable_unprepare(dwc->clk);
+	ret = pinctrl_pm_select_sleep_state(dev);
+	if (ret) {
+		dev_err(dev, "failed to select sleep state: %d\n", ret);
+		clk_prepare_enable(dwc->clk);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int eic7700_pwm_runtime_resume(struct device *dev)
+{
+	struct dwc_pwm_drvdata *data = dev_get_drvdata(dev);
+	struct pwm_chip *chip = data->chips[0];
+	struct dwc_pwm *dwc = to_dwc_pwm(chip);
+	int idx, ret;
+
+	ret = pinctrl_pm_select_default_state(dev);
+	if (ret) {
+		dev_err(dev, "failed to select default state: %d\n", ret);
+		return ret;
+	}
+
+	ret = clk_prepare_enable(dwc->clk);
+	if (ret) {
+		dev_err(dev, "failed to enable clock: %d\n", ret);
+		return ret;
+	}
+
+	for (idx = 0; idx < DW_PWMS_TOTAL; idx++) {
+		dwc_pwm_writel(dwc, dwc->ctx[idx].cnt, DWC_TIM_LD_CNT(idx));
+		dwc_pwm_writel(dwc, dwc->ctx[idx].cnt2, DWC_TIM_LD_CNT2(idx));
+		dwc_pwm_writel(dwc, dwc->ctx[idx].ctrl, DWC_TIM_CTRL(idx));
+	}
+
+	return 0;
+}
+
+static int eic7700_pwm_suspend(struct device *dev)
+{
+	int ret;
+
+	if (!pm_runtime_suspended(dev)) {
+		ret = eic7700_pwm_runtime_suspend(dev);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int eic7700_pwm_resume(struct device *dev)
+{
+	int ret;
+
+	if (!pm_runtime_suspended(dev)) {
+		ret = eic7700_pwm_runtime_resume(dev);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static const struct dev_pm_ops eic7700_pwm_pm_ops = {
+	RUNTIME_PM_OPS(eic7700_pwm_runtime_suspend, eic7700_pwm_runtime_resume,
+		       NULL)
+	SYSTEM_SLEEP_PM_OPS(eic7700_pwm_suspend, eic7700_pwm_resume)
+};
+
+static const struct of_device_id eic7700_pwm_id_table[] = {
+	{ .compatible = "eswin,eic7700-pwm", },
+	{ /* sentinel */ }