[PATCH 1/3] pwm: driver for qualcomm ipq6018 pwm block

[PATCH 1/3] pwm: driver for qualcomm ipq6018 pwm block

[Baruch Siach]

Driver for the PWM block in Qualcomm IPQ6018 line of SoCs. Based on
driver from downstream Codeaurora kernel tree. Removed support for older
(V1) variants because I have no access to that hardware.

Tested on IPQ6010 based hardware.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
---
 drivers/pwm/Kconfig   |  12 ++
 drivers/pwm/Makefile  |   1 +
 drivers/pwm/pwm-ipq.c | 263 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 276 insertions(+)
 create mode 100644 drivers/pwm/pwm-ipq.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 9a4f66ae8070..54ef62a27bdc 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -260,6 +260,18 @@ config PWM_INTEL_LGM
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-intel-lgm.
 
+config PWM_IPQ
+	tristate "IPQ PWM support"
+	depends on ARCH_QCOM || COMPILE_TEST
+	depends on HAVE_CLK && HAS_IOMEM
+	help
+	  Generic PWM framework driver for IPQ PWM block which supports
+	  4 pwm channels. Each of the these channels can be configured
+	  independent of each other.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-ipq.
+
 config PWM_IQS620A
 	tristate "Azoteq IQS620A PWM support"
 	depends on MFD_IQS62X || COMPILE_TEST
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 6374d3b1d6f3..73eb955dea1d 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -22,6 +22,7 @@ obj-$(CONFIG_PWM_IMX1)		+= pwm-imx1.o
 obj-$(CONFIG_PWM_IMX27)		+= pwm-imx27.o
 obj-$(CONFIG_PWM_IMX_TPM)	+= pwm-imx-tpm.o
 obj-$(CONFIG_PWM_INTEL_LGM)	+= pwm-intel-lgm.o
+obj-$(CONFIG_PWM_IPQ)		+= pwm-ipq.o
 obj-$(CONFIG_PWM_IQS620A)	+= pwm-iqs620a.o
 obj-$(CONFIG_PWM_JZ4740)	+= pwm-jz4740.o
 obj-$(CONFIG_PWM_KEEMBAY)	+= pwm-keembay.o
diff --git a/drivers/pwm/pwm-ipq.c b/drivers/pwm/pwm-ipq.c
new file mode 100644
index 000000000000..885cf885fcf6
--- /dev/null
+++ b/drivers/pwm/pwm-ipq.c
@@ -0,0 +1,263 @@
+// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
+/*
+ * Copyright (c) 2016-2017, 2020 The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <asm/div64.h>
+#include <linux/of_device.h>
+
+#define CLK_SRC_FREQ		(100*1000*1000)
+#define MAX_PWM_DEVICES		4
+
+/* The default period and duty cycle values to be configured. */
+#define DEFAULT_PERIOD_NS	10
+#define DEFAULT_DUTY_CYCLE_NS	5
+
+/*
+ * Enable bit is set to enable output toggling in pwm device.
+ * Update bit is set to reflect the changed divider and high duration
+ * values in register.
+ */
+#define PWM_ENABLE		0x80000000
+#define PWM_UPDATE		0x40000000
+
+/* The frequency range supported is 1Hz to 100MHz */
+#define MIN_PERIOD_NS	10
+#define MAX_PERIOD_NS	1000000000
+
+/*
+ * The max value specified for each field is based on the number of bits
+ * in the pwm control register for that field
+ */
+#define MAX_PWM_CFG		0xFFFF
+
+#define PWM_CTRL_HI_SHIFT	16
+
+#define PWM_CFG_REG0 0 /*PWM_DIV PWM_HI*/
+#define PWM_CFG_REG1 1 /*ENABLE UPDATE PWM_PRE_DIV*/
+
+struct ipq_pwm_chip {
+	struct pwm_chip chip;
+	struct clk *clk;
+	void __iomem *mem;
+};
+
+static struct ipq_pwm_chip *to_ipq_pwm_chip(struct pwm_chip *chip)
+{
+	return container_of(chip, struct ipq_pwm_chip, chip);
+}
+
+static unsigned ipq_pwm_reg_offset(struct pwm_device *pwm, unsigned reg)
+{
+	return ((pwm->hwpwm * 2) + reg) * 4;
+}
+
+static void config_div_and_duty(struct pwm_device *pwm, int pre_div,
+			unsigned long long pwm_div, unsigned long period_ns,
+			unsigned long long duty_ns)
+{
+	unsigned long hi_dur;
+	unsigned long long quotient;
+	unsigned long val = 0;
+	struct ipq_pwm_chip *ipq_chip = to_ipq_pwm_chip(pwm->chip);
+
+	/*
+	 * high duration = pwm duty * ( pwm div + 1)
+	 * pwm duty = duty_ns / period_ns
+	 */
+	quotient = (pwm_div + 1) * duty_ns;
+	do_div(quotient, period_ns);
+	hi_dur = quotient;
+
+	val |= ((hi_dur & MAX_PWM_CFG) << PWM_CTRL_HI_SHIFT);
+	val |= (pwm_div & MAX_PWM_CFG);
+	writel(val, ipq_chip->mem + ipq_pwm_reg_offset(pwm, PWM_CFG_REG0));
+	val = pre_div & MAX_PWM_CFG;
+	writel(val, ipq_chip->mem + ipq_pwm_reg_offset(pwm, PWM_CFG_REG1));
+}
+
+static int ipq_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct ipq_pwm_chip *ipq_chip = to_ipq_pwm_chip(pwm->chip);
+	unsigned offset = ipq_pwm_reg_offset(pwm, PWM_CFG_REG1);
+	unsigned long val;
+
+	val = readl(ipq_chip->mem + offset);
+	val |= (PWM_ENABLE | PWM_UPDATE);
+	writel(val, ipq_chip->mem + offset);
+
+	return 0;
+}
+
+static void ipq_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct ipq_pwm_chip *ipq_chip = to_ipq_pwm_chip(pwm->chip);
+	unsigned offset = ipq_pwm_reg_offset(pwm, PWM_CFG_REG1);
+	unsigned long val;
+
+	val = readl(ipq_chip->mem + offset);
+	val |= PWM_UPDATE;
+	val &= ~PWM_ENABLE;
+	writel(val, ipq_chip->mem + offset);
+}
+
+static int ipq_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
+						int duty_ns, int period_ns)
+{
+	struct ipq_pwm_chip *ipq_chip = to_ipq_pwm_chip(chip);
+	unsigned long freq;
+	int pre_div, close_pre_div, close_pwm_div;
+	int pwm_div;
+	long long diff;
+	unsigned long rate = clk_get_rate(ipq_chip->clk);
+	unsigned long min_diff = rate;
+	uint64_t fin_ps;
+
+	if (period_ns > MAX_PERIOD_NS || period_ns < MIN_PERIOD_NS) {
+		pr_err("PWM Frequency range supported is %dHz to %dHz\n"
+			"Switching to default configuration values\n",
+		       (int)NSEC_PER_SEC / MAX_PERIOD_NS,
+		       (int)NSEC_PER_SEC / MIN_PERIOD_NS);
+		period_ns = DEFAULT_PERIOD_NS;
+		duty_ns = DEFAULT_DUTY_CYCLE_NS;
+		pwm->state.period = period_ns;
+		pwm->state.duty_cycle = duty_ns;
+	}
+
+	/* freq in Hz for period in nano second*/
+	freq = NSEC_PER_SEC / period_ns;
+	fin_ps = (uint64_t)NSEC_PER_SEC * 1000;
+	do_div(fin_ps, rate);
+	close_pre_div = MAX_PWM_CFG;
+	close_pwm_div = MAX_PWM_CFG;
+
+	ipq_pwm_disable(chip, pwm);
+
+	for (pre_div = 0; pre_div <= MAX_PWM_CFG; pre_div++) {
+		pwm_div = DIV_ROUND_CLOSEST_ULL((uint64_t)period_ns * 1000,
+							fin_ps * (pre_div + 1));
+		pwm_div--;
+		if (pwm_div <= MAX_PWM_CFG) {
+			diff = (uint64_t)rate - ((uint64_t)freq * (pre_div + 1) * (pwm_div + 1));
+
+			if (diff < 0)
+				diff = -diff;
+			if (!diff) {
+				close_pre_div = pre_div;
+				close_pwm_div = pwm_div;
+				break;
+			}
+			if (diff < min_diff) {
+				min_diff = diff;
+				close_pre_div = pre_div;
+				close_pwm_div = pwm_div;
+			}
+		}
+	}
+
+	/* config divider values for the closest possible frequency */
+	config_div_and_duty(pwm, close_pre_div, close_pwm_div,
+					period_ns, duty_ns);
+	if (pwm->state.enabled)
+		ipq_pwm_enable(chip, pwm);
+
+	return 0;
+}
+
+static int ipq_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	pwm->state.period = DEFAULT_PERIOD_NS;
+	pwm->state.duty_cycle = DEFAULT_DUTY_CYCLE_NS;
+
+	ipq_pwm_config(chip, pwm, pwm->state.duty_cycle, pwm->state.period);
+
+	return 0;
+}
+
+static void ipq_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	ipq_pwm_disable(chip, pwm);
+}
+
+static struct pwm_ops ipq_pwm_ops = {
+	.request = ipq_pwm_request,
+	.free = ipq_pwm_free,
+	.config = ipq_pwm_config,
+	.enable = ipq_pwm_enable,
+	.disable = ipq_pwm_disable,
+	.owner = THIS_MODULE,
+};
+
+static int ipq_pwm_probe(struct platform_device *pdev)
+{
+	struct ipq_pwm_chip *pwm;
+	struct device *dev;
+	int ret;
+
+	dev = &pdev->dev;
+	pwm = devm_kzalloc(dev, sizeof(*pwm), GFP_KERNEL);
+	if (!pwm) {
+		dev_err(dev, "failed to allocate memory\n");
+		return -ENOMEM;
+	}
+
+	platform_set_drvdata(pdev, pwm);
+
+	pwm->mem = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(pwm->mem))
+		return PTR_ERR(pwm->mem);
+
+	pwm->clk = devm_clk_get(dev, "core");
+	if (!IS_ERR(pwm->clk)) {
+		ret = clk_set_rate(pwm->clk, CLK_SRC_FREQ);
+		if (ret)
+			return ret;
+		ret = clk_prepare_enable(pwm->clk);
+		if (ret)
+			return ret;
+	}
+
+	pwm->chip.dev = dev;
+	pwm->chip.ops = &ipq_pwm_ops;
+	pwm->chip.npwm = MAX_PWM_DEVICES;
+
+	ret = pwmchip_add(&pwm->chip);
+	if (ret < 0) {
+		dev_err(dev, "pwmchip_add() failed: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int ipq_pwm_remove(struct platform_device *pdev)
+{
+	struct ipq_pwm_chip *pwm = platform_get_drvdata(pdev);
+
+	return pwmchip_remove(&pwm->chip);
+}
+
+static const struct of_device_id pwm_ipq_dt_match[] = {
+	{ .compatible = "qcom,pwm-ipq6018", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, pwm_ipq_dt_match);
+
+static struct platform_driver ipq_pwm_driver = {
+	.driver = {
+		.name = "ipq-pwm",
+		.owner = THIS_MODULE,
+		.of_match_table = pwm_ipq_dt_match,
+	},
+	.probe = ipq_pwm_probe,
+	.remove = ipq_pwm_remove,
+};
+
+module_platform_driver(ipq_pwm_driver);
+
+MODULE_LICENSE("Dual BSD/GPL");
-- 
2.30.2

[PATCH 2/3] dt-bindings: pwm: add IPQ6018 binding

[Baruch Siach]

DT binding for the PWM block in Qualcomm IPQ6018 SoC.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
---
 .../devicetree/bindings/pwm/ipq-pwm.yaml      | 53 +++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/ipq-pwm.yaml

diff --git a/Documentation/devicetree/bindings/pwm/ipq-pwm.yaml b/Documentation/devicetree/bindings/pwm/ipq-pwm.yaml
new file mode 100644
index 000000000000..a98f20664702
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/ipq-pwm.yaml
@@ -0,0 +1,53 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pwm/ipq-pwm.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Qualcomm IPQ6018 PWM controller
+
+maintainers:
+  - Baruch Siach <baruch@tkos.co.il>
+
+properties:
+  "#pwm-cells":
+    description: |
+      Should be set to 2.
+
+  compatible:
+    const: qcom,pwm-ipq6018
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  clock-names:
+    const: core
+
+required:
+  - "#pwm-cells"
+  - compatible
+  - reg
+  - clocks
+  - clock-names
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/qcom,gcc-ipq6018.h>
+
+    soc {
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        pwm@1941010 {
+            #pwm-cells = <2>;
+            compatible = "qcom,pwm-ipq6018";
+            reg = <0x0 0x1941010 0x0 0x20>;
+            clocks = <&gcc GCC_ADSS_PWM_CLK>;
+            clock-names = "core";
+        };
+    };
-- 
2.30.2

Re: [PATCH 2/3] dt-bindings: pwm: add IPQ6018 binding

[Rob Herring]

On Wed, May 19, 2021 at 10:48:45AM +0300, Baruch Siach wrote:
> DT binding for the PWM block in Qualcomm IPQ6018 SoC.
> 
> Signed-off-by: Baruch Siach <baruch@tkos.co.il>
> ---
>  .../devicetree/bindings/pwm/ipq-pwm.yaml      | 53 +++++++++++++++++++
>  1 file changed, 53 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/pwm/ipq-pwm.yaml
> 
> diff --git a/Documentation/devicetree/bindings/pwm/ipq-pwm.yaml b/Documentation/devicetree/bindings/pwm/ipq-pwm.yaml
> new file mode 100644
> index 000000000000..a98f20664702
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pwm/ipq-pwm.yaml
> @@ -0,0 +1,53 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/pwm/ipq-pwm.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Qualcomm IPQ6018 PWM controller
> +
> +maintainers:
> +  - Baruch Siach <baruch@tkos.co.il>
> +
> +properties:
> +  "#pwm-cells":
> +    description: |
> +      Should be set to 2.

constraints, not free form text:

const: 2

> +
> +  compatible:
> +    const: qcom,pwm-ipq6018
> +
> +  reg:
> +    maxItems: 1
> +
> +  clocks:
> +    maxItems: 1
> +
> +  clock-names:
> +    const: core
> +
> +required:
> +  - "#pwm-cells"
> +  - compatible
> +  - reg
> +  - clocks
> +  - clock-names
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/clock/qcom,gcc-ipq6018.h>
> +
> +    soc {
> +        #address-cells = <2>;
> +        #size-cells = <2>;
> +
> +        pwm@1941010 {
> +            #pwm-cells = <2>;
> +            compatible = "qcom,pwm-ipq6018";
> +            reg = <0x0 0x1941010 0x0 0x20>;
> +            clocks = <&gcc GCC_ADSS_PWM_CLK>;
> +            clock-names = "core";
> +        };
> +    };
> -- 
> 2.30.2
> 

[PATCH 3/3] arm64: dts: ipq6018: add pwm node

[Baruch Siach]

Describe the PWM block on IPQ6018.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
---
 arch/arm64/boot/dts/qcom/ipq6018.dtsi | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/ipq6018.dtsi b/arch/arm64/boot/dts/qcom/ipq6018.dtsi
index 6ee7b99c21ec..2da75bb558ff 100644
--- a/arch/arm64/boot/dts/qcom/ipq6018.dtsi
+++ b/arch/arm64/boot/dts/qcom/ipq6018.dtsi
@@ -355,6 +355,15 @@ i2c_1: i2c@78b7000 { /* BLSP1 QUP2 */
 			status = "disabled";
 		};
 
+		pwm: pwm@1941010 {
+			#pwm-cells = <2>;
+			compatible = "qcom,pwm-ipq6018";
+			reg = <0x0 0x1941010 0x0 0x20>;
+			clocks = <&gcc GCC_ADSS_PWM_CLK>;
+			clock-names = "core";
+			status = "disabled";
+		};
+
 		qpic_bam: dma-controller@7984000 {
 			compatible = "qcom,bam-v1.7.0";
 			reg = <0x0 0x07984000 0x0 0x1a000>;
-- 
2.30.2

Re: [PATCH 1/3] pwm: driver for qualcomm ipq6018 pwm block

[Uwe Kleine-König]

[-- Attachment #1: Type: text/plain, Size: 11457 bytes --]

Hello Baruch,

On Wed, May 19, 2021 at 10:48:44AM +0300, Baruch Siach wrote:
> Driver for the PWM block in Qualcomm IPQ6018 line of SoCs. Based on
> driver from downstream Codeaurora kernel tree. Removed support for older
> (V1) variants because I have no access to that hardware.
> 
> Tested on IPQ6010 based hardware.
> 
> Signed-off-by: Baruch Siach <baruch@tkos.co.il>
> ---
>  drivers/pwm/Kconfig   |  12 ++
>  drivers/pwm/Makefile  |   1 +
>  drivers/pwm/pwm-ipq.c | 263 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 276 insertions(+)
>  create mode 100644 drivers/pwm/pwm-ipq.c
> 
> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index 9a4f66ae8070..54ef62a27bdc 100644
> --- a/drivers/pwm/Kconfig
> +++ b/drivers/pwm/Kconfig
> @@ -260,6 +260,18 @@ config PWM_INTEL_LGM
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called pwm-intel-lgm.
>  
> +config PWM_IPQ
> +	tristate "IPQ PWM support"
> +	depends on ARCH_QCOM || COMPILE_TEST
> +	depends on HAVE_CLK && HAS_IOMEM
> +	help
> +	  Generic PWM framework driver for IPQ PWM block which supports
> +	  4 pwm channels. Each of the these channels can be configured
> +	  independent of each other.
> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called pwm-ipq.
> +
>  config PWM_IQS620A
>  	tristate "Azoteq IQS620A PWM support"
>  	depends on MFD_IQS62X || COMPILE_TEST
> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> index 6374d3b1d6f3..73eb955dea1d 100644
> --- a/drivers/pwm/Makefile
> +++ b/drivers/pwm/Makefile
> @@ -22,6 +22,7 @@ obj-$(CONFIG_PWM_IMX1)		+= pwm-imx1.o
>  obj-$(CONFIG_PWM_IMX27)		+= pwm-imx27.o
>  obj-$(CONFIG_PWM_IMX_TPM)	+= pwm-imx-tpm.o
>  obj-$(CONFIG_PWM_INTEL_LGM)	+= pwm-intel-lgm.o
> +obj-$(CONFIG_PWM_IPQ)		+= pwm-ipq.o
>  obj-$(CONFIG_PWM_IQS620A)	+= pwm-iqs620a.o
>  obj-$(CONFIG_PWM_JZ4740)	+= pwm-jz4740.o
>  obj-$(CONFIG_PWM_KEEMBAY)	+= pwm-keembay.o
> diff --git a/drivers/pwm/pwm-ipq.c b/drivers/pwm/pwm-ipq.c
> new file mode 100644
> index 000000000000..885cf885fcf6
> --- /dev/null
> +++ b/drivers/pwm/pwm-ipq.c
> @@ -0,0 +1,263 @@
> +// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
> +/*
> + * Copyright (c) 2016-2017, 2020 The Linux Foundation. All rights reserved.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/pwm.h>
> +#include <linux/clk.h>
> +#include <linux/io.h>
> +#include <asm/div64.h>
> +#include <linux/of_device.h>
> +
> +#define CLK_SRC_FREQ		(100*1000*1000)
> +#define MAX_PWM_DEVICES		4
> +
> +/* The default period and duty cycle values to be configured. */
> +#define DEFAULT_PERIOD_NS	10
> +#define DEFAULT_DUTY_CYCLE_NS	5

These define's names are too generic. Please prefix them with your
driver's name.

> +/*
> + * Enable bit is set to enable output toggling in pwm device.
> + * Update bit is set to reflect the changed divider and high duration
> + * values in register.
> + */
> +#define PWM_ENABLE		0x80000000
> +#define PWM_UPDATE		0x40000000
> +
> +/* The frequency range supported is 1Hz to 100MHz */
> +#define MIN_PERIOD_NS	10
> +#define MAX_PERIOD_NS	1000000000
> +
> +/*
> + * The max value specified for each field is based on the number of bits
> + * in the pwm control register for that field
> + */
> +#define MAX_PWM_CFG		0xFFFF
> +
> +#define PWM_CTRL_HI_SHIFT	16
> +
> +#define PWM_CFG_REG0 0 /*PWM_DIV PWM_HI*/
> +#define PWM_CFG_REG1 1 /*ENABLE UPDATE PWM_PRE_DIV*/
> +
> +struct ipq_pwm_chip {
> +	struct pwm_chip chip;
> +	struct clk *clk;
> +	void __iomem *mem;
> +};
> +
> +static struct ipq_pwm_chip *to_ipq_pwm_chip(struct pwm_chip *chip)
> +{
> +	return container_of(chip, struct ipq_pwm_chip, chip);
> +}
> +
> +static unsigned ipq_pwm_reg_offset(struct pwm_device *pwm, unsigned reg)
> +{
> +	return ((pwm->hwpwm * 2) + reg) * 4;
> +}
> +
> +static void config_div_and_duty(struct pwm_device *pwm, int pre_div,
> +			unsigned long long pwm_div, unsigned long period_ns,
> +			unsigned long long duty_ns)
> +{
> +	unsigned long hi_dur;
> +	unsigned long long quotient;
> +	unsigned long val = 0;
> +	struct ipq_pwm_chip *ipq_chip = to_ipq_pwm_chip(pwm->chip);
> +
> +	/*
> +	 * high duration = pwm duty * ( pwm div + 1)

s/( /(/

> +	 * pwm duty = duty_ns / period_ns
> +	 */
> +	quotient = (pwm_div + 1) * duty_ns;
> +	do_div(quotient, period_ns);
> +	hi_dur = quotient;
> +
> +	val |= ((hi_dur & MAX_PWM_CFG) << PWM_CTRL_HI_SHIFT);
> +	val |= (pwm_div & MAX_PWM_CFG);
> +	writel(val, ipq_chip->mem + ipq_pwm_reg_offset(pwm, PWM_CFG_REG0));
> +	val = pre_div & MAX_PWM_CFG;
> +	writel(val, ipq_chip->mem + ipq_pwm_reg_offset(pwm, PWM_CFG_REG1));
> +}
> +
> +static int ipq_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> +	struct ipq_pwm_chip *ipq_chip = to_ipq_pwm_chip(pwm->chip);
> +	unsigned offset = ipq_pwm_reg_offset(pwm, PWM_CFG_REG1);
> +	unsigned long val;
> +
> +	val = readl(ipq_chip->mem + offset);
> +	val |= (PWM_ENABLE | PWM_UPDATE);

The parenthesis are not needed here.

> +	writel(val, ipq_chip->mem + offset);
> +
> +	return 0;
> +}
> +
> +static void ipq_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> +	struct ipq_pwm_chip *ipq_chip = to_ipq_pwm_chip(pwm->chip);
> +	unsigned offset = ipq_pwm_reg_offset(pwm, PWM_CFG_REG1);
> +	unsigned long val;
> +
> +	val = readl(ipq_chip->mem + offset);
> +	val |= PWM_UPDATE;

What is the effect of this register bit?

Does the output become inactive or does it freeze at state that happens
to be emitted when the ENABLE bit is removed?

> +	val &= ~PWM_ENABLE;
> +	writel(val, ipq_chip->mem + offset);
> +}
> +
> +static int ipq_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> +						int duty_ns, int period_ns)
> +{
> +	struct ipq_pwm_chip *ipq_chip = to_ipq_pwm_chip(chip);
> +	unsigned long freq;
> +	int pre_div, close_pre_div, close_pwm_div;
> +	int pwm_div;
> +	long long diff;
> +	unsigned long rate = clk_get_rate(ipq_chip->clk);
> +	unsigned long min_diff = rate;
> +	uint64_t fin_ps;
> +
> +	if (period_ns > MAX_PERIOD_NS || period_ns < MIN_PERIOD_NS) {
> +		pr_err("PWM Frequency range supported is %dHz to %dHz\n"
> +			"Switching to default configuration values\n",
> +		       (int)NSEC_PER_SEC / MAX_PERIOD_NS,
> +		       (int)NSEC_PER_SEC / MIN_PERIOD_NS);
> +		period_ns = DEFAULT_PERIOD_NS;
> +		duty_ns = DEFAULT_DUTY_CYCLE_NS;
> +		pwm->state.period = period_ns;
> +		pwm->state.duty_cycle = duty_ns;
> +	}

Please implement the biggest period not bigger than the requested
period. That is do something like:

	if (period_ns < MIN_PERIOD_NS)
		return -ERANGE;

	if (period_ns > MAX_PERIOD_NS)
		period_ns = MAX_PERIOD_NS;

> +
> +	/* freq in Hz for period in nano second*/
> +	freq = NSEC_PER_SEC / period_ns;
> +	fin_ps = (uint64_t)NSEC_PER_SEC * 1000;
> +	do_div(fin_ps, rate);
> +	close_pre_div = MAX_PWM_CFG;
> +	close_pwm_div = MAX_PWM_CFG;
> +
> +	ipq_pwm_disable(chip, pwm);

This is necessary?

> +	for (pre_div = 0; pre_div <= MAX_PWM_CFG; pre_div++) {
> +		pwm_div = DIV_ROUND_CLOSEST_ULL((uint64_t)period_ns * 1000,
> +							fin_ps * (pre_div + 1));
> +		pwm_div--;

What if pwm_div was 0 before? (Didn't check if this can happen, maybe it
doesn't with period_ns >= MIN_PERIOD_NS?)

> +		if (pwm_div <= MAX_PWM_CFG) {
> +			diff = (uint64_t)rate - ((uint64_t)freq * (pre_div + 1) * (pwm_div + 1));
> +
> +			if (diff < 0)
> +				diff = -diff;
> +			if (!diff) {
> +				close_pre_div = pre_div;
> +				close_pwm_div = pwm_div;
> +				break;
> +			}
> +			if (diff < min_diff) {
> +				min_diff = diff;
> +				close_pre_div = pre_div;
> +				close_pwm_div = pwm_div;
> +			}

As written above: Never pick a period bigger than the requested period.

> +		}
> +	}
> +
> +	/* config divider values for the closest possible frequency */
> +	config_div_and_duty(pwm, close_pre_div, close_pwm_div,
> +					period_ns, duty_ns);

Please align follow up lines to the opening (.

> +	if (pwm->state.enabled)
> +		ipq_pwm_enable(chip, pwm);
> +
> +	return 0;
> +}
> +
> +static int ipq_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> +	pwm->state.period = DEFAULT_PERIOD_NS;
> +	pwm->state.duty_cycle = DEFAULT_DUTY_CYCLE_NS;
> +
> +	ipq_pwm_config(chip, pwm, pwm->state.duty_cycle, pwm->state.period);

.request is not supposed to modify the emitted wave form.

> +
> +	return 0;
> +}
> +
> +static void ipq_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> +	ipq_pwm_disable(chip, pwm);

neither is .free.

> +}
> +
> +static struct pwm_ops ipq_pwm_ops = {
> +	.request = ipq_pwm_request,
> +	.free = ipq_pwm_free,
> +	.config = ipq_pwm_config,
> +	.enable = ipq_pwm_enable,
> +	.disable = ipq_pwm_disable,

Please implement .apply instead of .config/.enable/.disable.

If you had enabled PWM_DEBUG during your tests you would have noticed
yourself ...

> +	.owner = THIS_MODULE,
> +};
> +
> +static int ipq_pwm_probe(struct platform_device *pdev)
> +{
> +	struct ipq_pwm_chip *pwm;
> +	struct device *dev;
> +	int ret;
> +
> +	dev = &pdev->dev;
> +	pwm = devm_kzalloc(dev, sizeof(*pwm), GFP_KERNEL);
> +	if (!pwm) {
> +		dev_err(dev, "failed to allocate memory\n");

You're not supposed to emit a message for -ENOMEM type errors. This is
already loud enough.

> +		return -ENOMEM;
> +	}
> +
> +	platform_set_drvdata(pdev, pwm);
> +
> +	pwm->mem = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(pwm->mem))
> +		return PTR_ERR(pwm->mem);
> +
> +	pwm->clk = devm_clk_get(dev, "core");
> +	if (!IS_ERR(pwm->clk)) {

If devm_clk_get() returns an error you should return an error, too.
You might want to use devm_clk_get_optional().

> +		ret = clk_set_rate(pwm->clk, CLK_SRC_FREQ);
> +		if (ret)
> +			return ret;
> +		ret = clk_prepare_enable(pwm->clk);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	pwm->chip.dev = dev;
> +	pwm->chip.ops = &ipq_pwm_ops;
> +	pwm->chip.npwm = MAX_PWM_DEVICES;
> +
> +	ret = pwmchip_add(&pwm->chip);
> +	if (ret < 0) {
> +		dev_err(dev, "pwmchip_add() failed: %d\n", ret);
> +		return ret;

	return dev_err_probe(dev, ret, "...")

please. And you have to disable the clock again.

> +	}
> +
> +	return 0;
> +}
> +
> +static int ipq_pwm_remove(struct platform_device *pdev)
> +{
> +	struct ipq_pwm_chip *pwm = platform_get_drvdata(pdev);
> +
> +	return pwmchip_remove(&pwm->chip);

Please ignore the return value of pwmchip_remove(). This is eventually
changed to return void.

> +}
> +
> +static const struct of_device_id pwm_ipq_dt_match[] = {
> +	{ .compatible = "qcom,pwm-ipq6018", },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, pwm_ipq_dt_match);
> +
> +static struct platform_driver ipq_pwm_driver = {
> +	.driver = {
> +		.name = "ipq-pwm",
> +		.owner = THIS_MODULE,
> +		.of_match_table = pwm_ipq_dt_match,
> +	},
> +	.probe = ipq_pwm_probe,
> +	.remove = ipq_pwm_remove,
> +};
> +
> +module_platform_driver(ipq_pwm_driver);
> +
> +MODULE_LICENSE("Dual BSD/GPL");

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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Re: [PATCH 1/3] pwm: driver for qualcomm ipq6018 pwm block

[Baruch Siach]

Hi Uwe,

Thanks for your review comments.

On Sun, May 23 2021, Uwe Kleine-König wrote:
> On Wed, May 19, 2021 at 10:48:44AM +0300, Baruch Siach wrote:
>> Driver for the PWM block in Qualcomm IPQ6018 line of SoCs. Based on
>> driver from downstream Codeaurora kernel tree. Removed support for older
>> (V1) variants because I have no access to that hardware.
>> 
>> Tested on IPQ6010 based hardware.
>> 
>> Signed-off-by: Baruch Siach <baruch@tkos.co.il>

[...]

>> +static void ipq_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
>> +{
>> +	struct ipq_pwm_chip *ipq_chip = to_ipq_pwm_chip(pwm->chip);
>> +	unsigned offset = ipq_pwm_reg_offset(pwm, PWM_CFG_REG1);
>> +	unsigned long val;
>> +
>> +	val = readl(ipq_chip->mem + offset);
>> +	val |= PWM_UPDATE;
>
> What is the effect of this register bit?
>
> Does the output become inactive or does it freeze at state that happens
> to be emitted when the ENABLE bit is removed?

I don't know. PWM does not work when this bit is not set here. The
original downstream driver[1] does not set this bit on disable. But it
also enables PWM unconditionally on .config. I added the 'enabled' check
in .config, and then PWM stopped working even when enabled later. It was
only by accident (excess copy/paste) that I found this workaround.

A comment on the original code says that PWM_UPDATE is "auto cleared".
This is evidently not true on my hardware (IPQ6010). This might be true
for older variants of this PWM block. Unfortunately, I have no access to
hardware documentation.

[1] https://source.codeaurora.org/quic/qsdk/oss/kernel/linux-ipq-5.4/tree/drivers/pwm/pwm-ipq.c?h=NHSS.QSDK.11.4.1.r1&id=9e4627b7088b0c06ddd910c8770274d26613de9e

baruch

-- 
                                                     ~. .~   Tk Open Systems
=}------------------------------------------------ooO--U--Ooo------------{=
   - baruch@tkos.co.il - tel: +972.52.368.4656, http://www.tkos.co.il -

Re: [PATCH 1/3] pwm: driver for qualcomm ipq6018 pwm block

[Uwe Kleine-König]

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Hello again,

for v2 please make sure to add linux-pwm@vger.kernel.org to Cc.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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[PATCH 1/3] pwm: driver for qualcomm ipq6018 pwm block

[Baruch Siach]

From: Baruch Siach <baruch.siach@siklu.com>

Driver for the PWM block in Qualcomm IPQ6018 line of SoCs. Based on
driver from downstream Codeaurora kernel tree. Removed support for older
(V1) variants because I have no access to that hardware.

Tested on IPQ6010 based hardware.

Signed-off-by: Baruch Siach <baruch.siach@siklu.com>
---
v11:

Address comment from Uwe Kleine-König:

  Drop redundant registers field comments

  Fix period limit check in .apply

  Clarify the comment explaining skip of pre_div > pwm_div values

  Add explicit check for clock rate within limit

  Add comment explaining the selection of initial pre_div

  Use pwm_div division with remainder instead of separate diff calculation

  Round up duty_cycle calculation in .get_state

v10:

  Restore round up in pwm_div calculation; otherwise diff is always <=
  0, so only bingo match works

  Don't overwrite min_diff on every loop iteration

v9:

Address comment from Uwe Kleine-König:

  Use period_ns*rate in dividers calculation for better accuracy

  Round down pre_div and pwm_div

  Add a comment explaining why pwm_div can't underflow

  Add a comment explaining why pre_div > pwm_div end the search loop

  Drop 'CFG_' from register macros

  Rename to_ipq_pwm_chip() to ipq_pwm_from_chip()

  Change bare 'unsigned' to 'unsigned int'

  Clarify the comment on separate REG1 write for enable/disable

  Round up the period value in .get_state

  Use direct readl/writel so no need to check for regmap errors

v7:

  Change 'offset' to 'reg' for the tcsr offset (Rob)

  Drop clock name; there is only one clock (Bjorn)

  Simplify probe failure code path (Bjorn)

v6:

Address Uwe Kleine-König review comments:

  Drop IPQ_PWM_MAX_DEVICES

  Rely on assigned-clock-rates; drop IPQ_PWM_CLK_SRC_FREQ

  Simplify register offset calculation

  Calculate duty cycle more precisely

  Refuse to set inverted polarity

  Drop redundant IPQ_PWM_REG1_ENABLE bit clear

  Remove x1000 factor in pwm_div calculation, use rate directly, and round up

  Choose initial pre_div such that pwm_div < IPQ_PWM_MAX_DIV

  Ensure pre_div <= pwm_div

  Rename close_ to best_

  Explain in comment why effective_div doesn't overflow

  Limit pwm_div to IPQ_PWM_MAX_DIV - 1 to allow 100% duty cycle

  Disable clock only after pwmchip_remove()

  const pwm_ops

Other changes:

  Add missing linux/bitfield.h header include (kernel test robot)

  Adjust code for PWM device node under TCSR (Rob Herring)

v5:

Use &tcsr_q6 syscon to access registers (Bjorn Andersson)

Address Uwe Kleine-König review comments:

  Implement .get_state()

  Add IPQ_PWM_ prefix to local macros

  Use GENMASK/BIT/FIELD_PREP for register fields access

  Make type of config_div_and_duty() parameters consistent

  Derive IPQ_PWM_MIN_PERIOD_NS from IPQ_PWM_CLK_SRC_FREQ

  Integrate enable/disable into config_div_and_duty() to save register read,
  and reduce frequency glitch on update

  Use min() instead of min_t()

  Fix comment format

  Use dev_err_probe() to indicate probe step failure

  Add missing clk_disable_unprepare() in .remove

  Don't set .owner

v4:

  Use div64_u64() to fix link for 32-bit targets ((kernel test robot
  <lkp@intel.com>, Uwe Kleine-König)

v3:

  s/qcom,pwm-ipq6018/qcom,ipq6018-pwm/ (Rob Herring)

  Fix integer overflow on 32-bit targets (kernel test robot <lkp@intel.com>)

v2:

Address Uwe Kleine-König review comments:

  Fix period calculation when out of range

  Don't set period larger than requested

  Remove PWM disable on configuration change

  Implement .apply instead of non-atomic .config/.enable/.disable

  Don't modify PWM on .request/.free

  Check pwm_div underflow

  Fix various code and comment formatting issues

Other changes:

  Use u64 divisor safe division

  Remove now empty .request/.free
---
 drivers/pwm/Kconfig   |  12 ++
 drivers/pwm/Makefile  |   1 +
 drivers/pwm/pwm-ipq.c | 281 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 294 insertions(+)
 create mode 100644 drivers/pwm/pwm-ipq.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 21e3b05a5153..e39718137ecd 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -260,6 +260,18 @@ config PWM_INTEL_LGM
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-intel-lgm.
 
+config PWM_IPQ
+	tristate "IPQ PWM support"
+	depends on ARCH_QCOM || COMPILE_TEST
+	depends on HAVE_CLK && HAS_IOMEM
+	help
+	  Generic PWM framework driver for IPQ PWM block which supports
+	  4 pwm channels. Each of the these channels can be configured
+	  independent of each other.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-ipq.
+
 config PWM_IQS620A
 	tristate "Azoteq IQS620A PWM support"
 	depends on MFD_IQS62X || COMPILE_TEST
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 708840b7fba8..7402feae4b36 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -22,6 +22,7 @@ obj-$(CONFIG_PWM_IMX1)		+= pwm-imx1.o
 obj-$(CONFIG_PWM_IMX27)		+= pwm-imx27.o
 obj-$(CONFIG_PWM_IMX_TPM)	+= pwm-imx-tpm.o
 obj-$(CONFIG_PWM_INTEL_LGM)	+= pwm-intel-lgm.o
+obj-$(CONFIG_PWM_IPQ)		+= pwm-ipq.o
 obj-$(CONFIG_PWM_IQS620A)	+= pwm-iqs620a.o
 obj-$(CONFIG_PWM_JZ4740)	+= pwm-jz4740.o
 obj-$(CONFIG_PWM_KEEMBAY)	+= pwm-keembay.o
diff --git a/drivers/pwm/pwm-ipq.c b/drivers/pwm/pwm-ipq.c
new file mode 100644
index 000000000000..994027290bcb
--- /dev/null
+++ b/drivers/pwm/pwm-ipq.c
@@ -0,0 +1,281 @@
+// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
+/*
+ * Copyright (c) 2016-2017, 2020 The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/math64.h>
+#include <linux/of_device.h>
+#include <linux/bitfield.h>
+#include <linux/units.h>
+
+/* The frequency range supported is 1 Hz to clock rate */
+#define IPQ_PWM_MAX_PERIOD_NS	((u64)NSEC_PER_SEC)
+
+/*
+ * The max value specified for each field is based on the number of bits
+ * in the pwm control register for that field
+ */
+#define IPQ_PWM_MAX_DIV		0xFFFF
+
+/*
+ * Two 32-bit registers for each PWM: REG0, and REG1.
+ * Base offset for PWM #i is at 8 * #i.
+ */
+#define IPQ_PWM_REG0			0
+#define IPQ_PWM_REG0_PWM_DIV		GENMASK(15, 0)
+#define IPQ_PWM_REG0_HI_DURATION	GENMASK(31, 16)
+
+#define IPQ_PWM_REG1			4
+#define IPQ_PWM_REG1_PRE_DIV		GENMASK(15, 0)
+/*
+ * Enable bit is set to enable output toggling in pwm device.
+ * Update bit is set to reflect the changed divider and high duration
+ * values in register.
+ */
+#define IPQ_PWM_REG1_UPDATE		BIT(30)
+#define IPQ_PWM_REG1_ENABLE		BIT(31)
+
+
+struct ipq_pwm_chip {
+	struct pwm_chip chip;
+	struct clk *clk;
+	void __iomem *mem;
+};
+
+static struct ipq_pwm_chip *ipq_pwm_from_chip(struct pwm_chip *chip)
+{
+	return container_of(chip, struct ipq_pwm_chip, chip);
+}
+
+static unsigned int ipq_pwm_reg_read(struct pwm_device *pwm, unsigned int reg)
+{
+	struct ipq_pwm_chip *ipq_chip = ipq_pwm_from_chip(pwm->chip);
+	unsigned int off = 8 * pwm->hwpwm + reg;
+
+	return readl(ipq_chip->mem + off);
+}
+
+static void ipq_pwm_reg_write(struct pwm_device *pwm, unsigned int reg,
+			      unsigned int val)
+{
+	struct ipq_pwm_chip *ipq_chip = ipq_pwm_from_chip(pwm->chip);
+	unsigned int off = 8 * pwm->hwpwm + reg;
+
+	writel(val, ipq_chip->mem + off);
+}
+
+static void config_div_and_duty(struct pwm_device *pwm, unsigned int pre_div,
+			unsigned int pwm_div, unsigned long rate, u64 duty_ns,
+			bool enable)
+{
+	unsigned long hi_dur;
+	unsigned long val = 0;
+
+	/*
+	 * high duration = pwm duty * (pwm div + 1)
+	 * pwm duty = duty_ns / period_ns
+	 */
+	hi_dur = div64_u64(duty_ns * rate, (pre_div + 1) * NSEC_PER_SEC);
+
+	val = FIELD_PREP(IPQ_PWM_REG0_HI_DURATION, hi_dur) |
+		FIELD_PREP(IPQ_PWM_REG0_PWM_DIV, pwm_div);
+	ipq_pwm_reg_write(pwm, IPQ_PWM_REG0, val);
+
+	val = FIELD_PREP(IPQ_PWM_REG1_PRE_DIV, pre_div);
+	ipq_pwm_reg_write(pwm, IPQ_PWM_REG1, val);
+
+	/* PWM enable toggle needs a separate write to REG1 */
+	val |= IPQ_PWM_REG1_UPDATE;
+	if (enable)
+		val |= IPQ_PWM_REG1_ENABLE;
+	ipq_pwm_reg_write(pwm, IPQ_PWM_REG1, val);
+}
+
+static int ipq_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			 const struct pwm_state *state)
+{
+	struct ipq_pwm_chip *ipq_chip = ipq_pwm_from_chip(chip);
+	unsigned int pre_div, pwm_div, best_pre_div, best_pwm_div;
+	unsigned long rate = clk_get_rate(ipq_chip->clk);
+	u64 period_ns, duty_ns, period_rate;
+	u64 min_diff;
+
+	if (state->polarity != PWM_POLARITY_NORMAL)
+		return -EINVAL;
+
+	if (state->period < DIV64_U64_ROUND_UP(NSEC_PER_SEC, rate))
+		return -ERANGE;
+
+	period_ns = min(state->period, IPQ_PWM_MAX_PERIOD_NS);
+	duty_ns = min(state->duty_cycle, period_ns);
+
+	/*
+	 * period_ns is 1G or less. As long as rate is less than 16 GHz,
+	 * period_rate does not overflow. Make that explicit.
+	 */
+	if (rate > 16ULL * GIGA)
+		return -EINVAL;
+	period_rate = period_ns * rate;
+	best_pre_div = IPQ_PWM_MAX_DIV;
+	best_pwm_div = IPQ_PWM_MAX_DIV;
+	/*
+	 * We don't need to consider pre_div values smaller than
+	 *
+	 *                              period_rate
+	 *  pre_div_min := ------------------------------------
+	 *                 NSEC_PER_SEC * (IPQ_PWM_MAX_DIV + 1)
+	 *
+	 * because pre_div = pre_div_min results in a better
+	 * approximation.
+	 */
+	pre_div = div64_u64(period_rate,
+			(u64)NSEC_PER_SEC * (IPQ_PWM_MAX_DIV + 1));
+	min_diff = period_rate;
+
+	for (; pre_div <= IPQ_PWM_MAX_DIV; pre_div++) {
+		u64 remainder;
+
+		pwm_div = div64_u64_rem(period_rate,
+				(u64)NSEC_PER_SEC * (pre_div + 1), &remainder);
+		/* pwm_div is unsigned; the check below catches underflow */
+		pwm_div--;
+
+		/*
+		 * Swapping values for pre_div and pwm_div produces the same
+		 * period length. So we can skip all settings with pre_div >
+		 * pwm_div which results in bigger constraints for selecting
+		 * the duty_cycle than with the two values swapped.
+		 */
+		if (pre_div > pwm_div)
+			break;
+
+		/*
+		 * Make sure we can do 100% duty cycle where
+		 * hi_dur == pwm_div + 1
+		 */
+		if (pwm_div > IPQ_PWM_MAX_DIV - 1)
+			continue;
+
+		if (remainder < min_diff) {
+			best_pre_div = pre_div;
+			best_pwm_div = pwm_div;
+			min_diff = remainder;
+
+			if (min_diff == 0) /* bingo */
+				break;
+		}
+	}
+
+	/* config divider values for the closest possible frequency */
+	config_div_and_duty(pwm, best_pre_div, best_pwm_div,
+			    rate, duty_ns, state->enabled);
+
+	return 0;
+}
+
+static void ipq_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+			      struct pwm_state *state)
+{
+	struct ipq_pwm_chip *ipq_chip = ipq_pwm_from_chip(chip);
+	unsigned long rate = clk_get_rate(ipq_chip->clk);
+	unsigned int pre_div, pwm_div, hi_dur;
+	u64 effective_div, hi_div;
+	u32 reg0, reg1;
+
+	reg0 = ipq_pwm_reg_read(pwm, IPQ_PWM_REG0);
+	reg1 = ipq_pwm_reg_read(pwm, IPQ_PWM_REG1);
+
+	state->polarity = PWM_POLARITY_NORMAL;
+	state->enabled = reg1 & IPQ_PWM_REG1_ENABLE;
+
+	pwm_div = FIELD_GET(IPQ_PWM_REG0_PWM_DIV, reg0);
+	hi_dur = FIELD_GET(IPQ_PWM_REG0_HI_DURATION, reg0);
+	pre_div = FIELD_GET(IPQ_PWM_REG1_PRE_DIV, reg1);
+
+	/* No overflow here, both pre_div and pwm_div <= 0xffff */
+	effective_div = (u64)(pre_div + 1) * (pwm_div + 1);
+	state->period = DIV64_U64_ROUND_UP(effective_div * NSEC_PER_SEC, rate);
+
+	hi_div = hi_dur * (pre_div + 1);
+	state->duty_cycle = DIV64_U64_ROUND_UP(hi_div * NSEC_PER_SEC, rate);
+}
+
+static const struct pwm_ops ipq_pwm_ops = {
+	.apply = ipq_pwm_apply,
+	.get_state = ipq_pwm_get_state,
+	.owner = THIS_MODULE,
+};
+
+static int ipq_pwm_probe(struct platform_device *pdev)
+{
+	struct ipq_pwm_chip *pwm;
+	struct device *dev = &pdev->dev;
+	int ret;
+
+	pwm = devm_kzalloc(dev, sizeof(*pwm), GFP_KERNEL);
+	if (!pwm)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, pwm);
+
+	pwm->mem = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(pwm->mem))
+		return dev_err_probe(dev, PTR_ERR(pwm->mem),
+				"regs map failed");
+
+	pwm->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(pwm->clk))
+		return dev_err_probe(dev, PTR_ERR(pwm->clk),
+				"failed to get clock");
+
+	ret = clk_prepare_enable(pwm->clk);
+	if (ret)
+		return dev_err_probe(dev, ret, "clock enable failed");
+
+	pwm->chip.dev = dev;
+	pwm->chip.ops = &ipq_pwm_ops;
+	pwm->chip.npwm = 4;
+
+	ret = pwmchip_add(&pwm->chip);
+	if (ret < 0) {
+		dev_err_probe(dev, ret, "pwmchip_add() failed\n");
+		clk_disable_unprepare(pwm->clk);
+	}
+
+	return ret;
+}
+
+static int ipq_pwm_remove(struct platform_device *pdev)
+{
+	struct ipq_pwm_chip *pwm = platform_get_drvdata(pdev);
+
+	pwmchip_remove(&pwm->chip);
+	clk_disable_unprepare(pwm->clk);
+
+	return 0;
+}
+
+static const struct of_device_id pwm_ipq_dt_match[] = {
+	{ .compatible = "qcom,ipq6018-pwm", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, pwm_ipq_dt_match);
+
+static struct platform_driver ipq_pwm_driver = {
+	.driver = {
+		.name = "ipq-pwm",
+		.of_match_table = pwm_ipq_dt_match,
+	},
+	.probe = ipq_pwm_probe,
+	.remove = ipq_pwm_remove,
+};
+
+module_platform_driver(ipq_pwm_driver);
+
+MODULE_LICENSE("Dual BSD/GPL");
-- 
2.34.1

[PATCH 3/3] arm64: dts: ipq6018: add pwm node

[Baruch Siach]

From: Baruch Siach <baruch.siach@siklu.com>

Describe the PWM block on IPQ6018.

The PWM is in the TCSR area. Make &tcsr "simple-mfd" compatible, and add
&pwm as child of &tcsr.

Add also ipq6018 specific compatible string.

Signed-off-by: Baruch Siach <baruch.siach@siklu.com>
---
v9:

  Add 'ranges' property (Rob)

v8:

  Add size cell to 'reg' (Rob)

v7:

  Use 'reg' instead of 'offset' (Rob)

  Add qcom,tcsr-ipq6018 (Rob)

  Drop clock-names (Bjorn)

v6:

  Make the PWM node child of TCSR (Rob Herring)

  Add assigned-clocks/assigned-clock-rates (Uwe Kleine-König)

v5: Use qcom,pwm-regs for TCSR phandle instead of direct regs

v3: s/qcom,pwm-ipq6018/qcom,ipq6018-pwm/ (Rob Herring)
---
 arch/arm64/boot/dts/qcom/ipq6018.dtsi | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/qcom/ipq6018.dtsi b/arch/arm64/boot/dts/qcom/ipq6018.dtsi
index 66ec5615651d..a717fc17523d 100644
--- a/arch/arm64/boot/dts/qcom/ipq6018.dtsi
+++ b/arch/arm64/boot/dts/qcom/ipq6018.dtsi
@@ -258,8 +258,21 @@ tcsr_mutex_regs: syscon@1905000 {
 		};
 
 		tcsr: syscon@1937000 {
-			compatible = "syscon";
+			compatible = "qcom,tcsr-ipq6018", "syscon", "simple-mfd";
 			reg = <0x0 0x01937000 0x0 0x21000>;
+			#address-cells = <1>;
+			#size-cells = <1>;
+			ranges = <0x0 0x0 0x01937000 0x21000>;
+
+			pwm: pwm@a010 {
+				compatible = "qcom,ipq6018-pwm";
+				reg = <0xa010 0x20>;
+				clocks = <&gcc GCC_ADSS_PWM_CLK>;
+				assigned-clocks = <&gcc GCC_ADSS_PWM_CLK>;
+				assigned-clock-rates = <100000000>;
+				#pwm-cells = <2>;
+				status = "disabled";
+			};
 		};
 
 		blsp_dma: dma-controller@7884000 {
-- 
2.34.1