[PATCH v6 1/4] arm64: dts: ipq6018: correct TCSR block area

[PATCH v6 1/4] arm64: dts: ipq6018: correct TCSR block area

[Baruch Siach]

According to Bjorn Andersson[1], &tcsr_q6 base is 0x01937000 with size
0x21000. Adjust qcom,halt-regs offsets (add 0xe000) to match the new
syscon base.

Also, rename to just &tcsr as Kathiravan T suggested.

[1] https://lore.kernel.org/r/YLgO0Aj1d4w9EcPv@yoga

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
---
v6:

  Fix offset adjust (Kathiravan T)

  Rename &tcsr_q6 to &tcsr (Kathiravan T)

v5: New patch in this series
---
 arch/arm64/boot/dts/qcom/ipq6018.dtsi | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/boot/dts/qcom/ipq6018.dtsi b/arch/arm64/boot/dts/qcom/ipq6018.dtsi
index 6ee7b99c21ec..6bb262757cd9 100644
--- a/arch/arm64/boot/dts/qcom/ipq6018.dtsi
+++ b/arch/arm64/boot/dts/qcom/ipq6018.dtsi
@@ -270,9 +270,9 @@ tcsr_mutex_regs: syscon@1905000 {
 			reg = <0x0 0x01905000 0x0 0x8000>;
 		};
 
-		tcsr_q6: syscon@1945000 {
+		tcsr: syscon@1937000 {
 			compatible = "syscon";
-			reg = <0x0 0x01945000 0x0 0xe000>;
+			reg = <0x0 0x01937000 0x0 0x21000>;
 		};
 
 		blsp_dma: dma-controller@7884000 {
@@ -615,7 +615,7 @@ q6v5_wcss: remoteproc@cd00000 {
 			clocks = <&gcc GCC_PRNG_AHB_CLK>;
 			clock-names = "prng";
 
-			qcom,halt-regs = <&tcsr_q6 0xa000 0xd000 0x0>;
+			qcom,halt-regs = <&tcsr 0x18000 0x1b000 0xe000>;
 
 			qcom,smem-states = <&wcss_smp2p_out 0>,
 					   <&wcss_smp2p_out 1>;
-- 
2.30.2

[PATCH v6 2/4] 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>
---
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 | 276 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 289 insertions(+)
 create mode 100644 drivers/pwm/pwm-ipq.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index c76adedd58c9..08add845596f 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..19f7ed93dc81
--- /dev/null
+++ b/drivers/pwm/pwm-ipq.c
@@ -0,0 +1,276 @@
+// 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/mfd/syscon.h>
+#include <linux/regmap.h>
+#include <linux/bitfield.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_CFG_REG0 0 /*PWM_DIV PWM_HI*/
+#define IPQ_PWM_REG0_PWM_DIV		GENMASK(15, 0)
+#define IPQ_PWM_REG0_HI_DURATION	GENMASK(31, 16)
+
+#define IPQ_PWM_CFG_REG1 4 /*ENABLE UPDATE PWM_PRE_DIV*/
+#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;
+	struct regmap *regmap;
+	u32 regmap_off;
+};
+
+static struct ipq_pwm_chip *to_ipq_pwm_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 reg)
+{
+	struct ipq_pwm_chip *ipq_chip = to_ipq_pwm_chip(pwm->chip);
+	unsigned int off = ipq_chip->regmap_off + 8 * pwm->hwpwm + reg;
+	unsigned int val;
+
+	regmap_read(ipq_chip->regmap, off, &val);
+
+	return val;
+}
+
+static void ipq_pwm_reg_write(struct pwm_device *pwm, unsigned reg,
+		unsigned val)
+{
+	struct ipq_pwm_chip *ipq_chip = to_ipq_pwm_chip(pwm->chip);
+	unsigned int off = ipq_chip->regmap_off + 8 * pwm->hwpwm + reg;
+
+	regmap_write(ipq_chip->regmap, off, val);
+}
+
+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_CFG_REG0, val);
+
+	val = FIELD_PREP(IPQ_PWM_REG1_PRE_DIV, pre_div);
+	ipq_pwm_reg_write(pwm, IPQ_PWM_CFG_REG1, val);
+
+	/* Enable 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_CFG_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 = to_ipq_pwm_chip(chip);
+	unsigned long freq;
+	unsigned int pre_div, pwm_div, best_pre_div, best_pwm_div;
+	long long diff;
+	unsigned long rate = clk_get_rate(ipq_chip->clk);
+	unsigned long min_diff = rate;
+	u64 period_ns, duty_ns;
+
+	if (state->polarity != PWM_POLARITY_NORMAL)
+		return -EINVAL;
+
+	if (state->period < div64_u64(NSEC_PER_SEC, rate))
+		return -ERANGE;
+
+	period_ns = min(state->period, IPQ_PWM_MAX_PERIOD_NS);
+	duty_ns = min(state->duty_cycle, period_ns);
+
+	/* freq in Hz for period in nano second */
+	freq = div64_u64(NSEC_PER_SEC, period_ns);
+	best_pre_div = IPQ_PWM_MAX_DIV;
+	best_pwm_div = IPQ_PWM_MAX_DIV;
+	/* Initial pre_div value such that pwm_div < IPQ_PWM_MAX_DIV */
+	pre_div = DIV64_U64_ROUND_UP(period_ns * rate,
+			(u64)NSEC_PER_SEC * (IPQ_PWM_MAX_DIV + 1));
+
+	for (; pre_div <= IPQ_PWM_MAX_DIV; pre_div++) {
+		pwm_div = DIV64_U64_ROUND_UP(period_ns * rate,
+				(u64)NSEC_PER_SEC * (pre_div + 1));
+		pwm_div--;
+
+		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;
+
+		diff = ((uint64_t)freq * (pre_div + 1) * (pwm_div + 1))
+			- (uint64_t)rate;
+
+		if (diff < 0) /* period larger than requested */
+			continue;
+		if (diff == 0) { /* bingo */
+			best_pre_div = pre_div;
+			best_pwm_div = pwm_div;
+			break;
+		}
+		if (diff < min_diff) {
+			min_diff = diff;
+			best_pre_div = pre_div;
+			best_pwm_div = pwm_div;
+		}
+	}
+
+	/* 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 = to_ipq_pwm_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_CFG_REG0);
+	reg1 = ipq_pwm_reg_read(pwm, IPQ_PWM_CFG_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(effective_div * NSEC_PER_SEC, rate);
+
+	hi_div = hi_dur * (pre_div + 1);
+	state->duty_cycle = div64_u64(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->regmap = syscon_node_to_regmap(dev->parent->of_node);
+	if (IS_ERR(pwm->regmap))
+		return dev_err_probe(dev, PTR_ERR(pwm->regmap),
+				"regs map failed");
+
+	ret = of_property_read_u32(dev->of_node, "offset", &pwm->regmap_off);
+	if (ret)
+		return dev_err_probe(dev, ret, "error reading 'offset'");
+
+	pwm->clk = devm_clk_get(dev, "core");
+	if (IS_ERR(pwm->clk))
+		return dev_err_probe(dev, PTR_ERR(pwm->clk),
+				"failed to get core 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;
+	}
+
+	return 0;
+}
+
+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");
-- 
2.30.2

[PATCH v6 3/4] 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>
---
v6:

  Device node is child of TCSR; remove phandle (Rob Herring)

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

v5: Use qcom,pwm-regs for phandle instead of direct regs (Bjorn
    Andersson, Kathiravan T)

v4: Update the binding example node as well (Rob Herring's bot)

v3: s/qcom,pwm-ipq6018/qcom,ipq6018-pwm/ (Rob Herring)

v2: Make #pwm-cells const (Rob Herring)
---
 .../devicetree/bindings/pwm/ipq-pwm.yaml      | 69 +++++++++++++++++++
 1 file changed, 69 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..ee2bb03a1223
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/ipq-pwm.yaml
@@ -0,0 +1,69 @@
+# 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":
+    const: 2
+
+  compatible:
+    const: qcom,ipq6018-pwm
+
+  offset:
+    description: |
+      Offset of PWM register in the TCSR block.
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  clock-names:
+    const: core
+
+  assigned-clocks:
+    maxItems: 1
+
+  assigned-clock-rates:
+    maxItems: 1
+
+required:
+  - "#pwm-cells"
+  - compatible
+  - clocks
+  - clock-names
+  - assigned-clocks
+  - assigned-clock-rates
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/qcom,gcc-ipq6018.h>
+
+    soc {
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        tcsr: syscon@1937000 {
+            compatible = "syscon", "simple-mfd";
+            reg = <0x0 0x01937000 0x0 0x21000>;
+
+            pwm: pwm {
+                #pwm-cells = <2>;
+                compatible = "qcom,ipq6018-pwm";
+                offset = <0xa010>;
+                clocks = <&gcc GCC_ADSS_PWM_CLK>;
+                clock-names = "core";
+                assigned-clocks = <&gcc GCC_ADSS_PWM_CLK>;
+                assigned-clock-rates = <100000000>;
+                status = "disabled";
+            };
+        };
+    };
-- 
2.30.2

[PATCH v6 4/4] arm64: dts: ipq6018: add pwm node

[Baruch Siach]

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.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
---
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 | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/qcom/ipq6018.dtsi b/arch/arm64/boot/dts/qcom/ipq6018.dtsi
index 6bb262757cd9..2a95a24175ad 100644
--- a/arch/arm64/boot/dts/qcom/ipq6018.dtsi
+++ b/arch/arm64/boot/dts/qcom/ipq6018.dtsi
@@ -271,8 +271,19 @@ tcsr_mutex_regs: syscon@1905000 {
 		};
 
 		tcsr: syscon@1937000 {
-			compatible = "syscon";
+			compatible = "syscon", "simple-mfd";
 			reg = <0x0 0x01937000 0x0 0x21000>;
+
+			pwm: pwm {
+				#pwm-cells = <2>;
+				compatible = "qcom,ipq6018-pwm";
+				offset = <0xa010>;
+				clocks = <&gcc GCC_ADSS_PWM_CLK>;
+				clock-names = "core";
+				assigned-clocks = <&gcc GCC_ADSS_PWM_CLK>;
+				assigned-clock-rates = <100000000>;
+				status = "disabled";
+			};
 		};
 
 		blsp_dma: dma-controller@7884000 {
-- 
2.30.2

Re: [PATCH v6 3/4] dt-bindings: pwm: add IPQ6018 binding

[Rob Herring]

On Thu, Jul 22, 2021 at 01:01:09PM +0300, Baruch Siach wrote:
> DT binding for the PWM block in Qualcomm IPQ6018 SoC.
> 
> Signed-off-by: Baruch Siach <baruch@tkos.co.il>
> ---
> v6:
> 
>   Device node is child of TCSR; remove phandle (Rob Herring)
> 
>   Add assigned-clocks/assigned-clock-rates (Uwe Kleine-König)
> 
> v5: Use qcom,pwm-regs for phandle instead of direct regs (Bjorn
>     Andersson, Kathiravan T)
> 
> v4: Update the binding example node as well (Rob Herring's bot)
> 
> v3: s/qcom,pwm-ipq6018/qcom,ipq6018-pwm/ (Rob Herring)
> 
> v2: Make #pwm-cells const (Rob Herring)
> ---
>  .../devicetree/bindings/pwm/ipq-pwm.yaml      | 69 +++++++++++++++++++
>  1 file changed, 69 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..ee2bb03a1223
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pwm/ipq-pwm.yaml
> @@ -0,0 +1,69 @@
> +# 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":
> +    const: 2
> +
> +  compatible:
> +    const: qcom,ipq6018-pwm
> +
> +  offset:
> +    description: |
> +      Offset of PWM register in the TCSR block.
> +    maxItems: 1

Use 'reg' here instead.

> +
> +  clocks:
> +    maxItems: 1
> +
> +  clock-names:
> +    const: core
> +
> +  assigned-clocks:
> +    maxItems: 1
> +
> +  assigned-clock-rates:
> +    maxItems: 1
> +
> +required:
> +  - "#pwm-cells"
> +  - compatible
> +  - clocks
> +  - clock-names
> +  - assigned-clocks
> +  - assigned-clock-rates
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/clock/qcom,gcc-ipq6018.h>
> +
> +    soc {
> +        #address-cells = <2>;
> +        #size-cells = <2>;
> +
> +        tcsr: syscon@1937000 {
> +            compatible = "syscon", "simple-mfd";

This should really have a specific compatible string, but we don't warn 
for that (yet).

> +            reg = <0x0 0x01937000 0x0 0x21000>;
> +
> +            pwm: pwm {
> +                #pwm-cells = <2>;
> +                compatible = "qcom,ipq6018-pwm";
> +                offset = <0xa010>;
> +                clocks = <&gcc GCC_ADSS_PWM_CLK>;
> +                clock-names = "core";
> +                assigned-clocks = <&gcc GCC_ADSS_PWM_CLK>;
> +                assigned-clock-rates = <100000000>;
> +                status = "disabled";

Drop 'status'

> +            };
> +        };
> +    };
> -- 
> 2.30.2
> 
> 

Re: [PATCH v6 3/4] dt-bindings: pwm: add IPQ6018 binding

[Bjorn Andersson]

On Thu 22 Jul 05:01 CDT 2021, Baruch Siach wrote:

> DT binding for the PWM block in Qualcomm IPQ6018 SoC.
> 
> Signed-off-by: Baruch Siach <baruch@tkos.co.il>
> ---
> v6:
> 
>   Device node is child of TCSR; remove phandle (Rob Herring)
> 
>   Add assigned-clocks/assigned-clock-rates (Uwe Kleine-König)
> 
> v5: Use qcom,pwm-regs for phandle instead of direct regs (Bjorn
>     Andersson, Kathiravan T)
> 
> v4: Update the binding example node as well (Rob Herring's bot)
> 
> v3: s/qcom,pwm-ipq6018/qcom,ipq6018-pwm/ (Rob Herring)
> 
> v2: Make #pwm-cells const (Rob Herring)
> ---
>  .../devicetree/bindings/pwm/ipq-pwm.yaml      | 69 +++++++++++++++++++
>  1 file changed, 69 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..ee2bb03a1223
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pwm/ipq-pwm.yaml
> @@ -0,0 +1,69 @@
> +# 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":
> +    const: 2
> +
> +  compatible:
> +    const: qcom,ipq6018-pwm
> +
> +  offset:
> +    description: |

'|' maintains the formatting of the text, you don't need that.

> +      Offset of PWM register in the TCSR block.
> +    maxItems: 1
> +
> +  clocks:
> +    maxItems: 1
> +
> +  clock-names:
> +    const: core

With a single clock, it's nice to skip the -names.

> +
> +  assigned-clocks:
> +    maxItems: 1
> +
> +  assigned-clock-rates:
> +    maxItems: 1

These (assigned-*) are generic properties that may be used on a lot of
nodes, should they really be part of the individual binding, Rob?

> +
> +required:
> +  - "#pwm-cells"
> +  - compatible
> +  - clocks
> +  - clock-names
> +  - assigned-clocks
> +  - assigned-clock-rates
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/clock/qcom,gcc-ipq6018.h>
> +
> +    soc {
> +        #address-cells = <2>;
> +        #size-cells = <2>;
> +

Skip soc and *-cells...

> +        tcsr: syscon@1937000 {
> +            compatible = "syscon", "simple-mfd";
> +            reg = <0x0 0x01937000 0x0 0x21000>;
> +

..and just make this "reg = <0x01937000 0x21000>", in the example. Then
as we put this in the particular dts we adjust for whatever *-cells that
has defined for the parent bus.

> +            pwm: pwm {
> +                #pwm-cells = <2>;

I know it's important that this is a pwm thing, but I would prefer to
see the node start with compatible, offset/reg, clocks. And then end
with whatever is exposed (i.e. #pwm-cells)

Regards,
Bjorn

> +                compatible = "qcom,ipq6018-pwm";
> +                offset = <0xa010>;
> +                clocks = <&gcc GCC_ADSS_PWM_CLK>;
> +                clock-names = "core";
> +                assigned-clocks = <&gcc GCC_ADSS_PWM_CLK>;
> +                assigned-clock-rates = <100000000>;
> +                status = "disabled";
> +            };
> +        };
> +    };
> -- 
> 2.30.2
> 

Re: [PATCH v6 2/4] pwm: driver for qualcomm ipq6018 pwm block

[Bjorn Andersson]

On Thu 22 Jul 05:01 CDT 2021, 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>
> ---
> 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 | 276 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 289 insertions(+)
>  create mode 100644 drivers/pwm/pwm-ipq.c
> 
> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index c76adedd58c9..08add845596f 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..19f7ed93dc81
> --- /dev/null
> +++ b/drivers/pwm/pwm-ipq.c
> @@ -0,0 +1,276 @@
> +// 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/mfd/syscon.h>
> +#include <linux/regmap.h>
> +#include <linux/bitfield.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_CFG_REG0 0 /*PWM_DIV PWM_HI*/
> +#define IPQ_PWM_REG0_PWM_DIV		GENMASK(15, 0)
> +#define IPQ_PWM_REG0_HI_DURATION	GENMASK(31, 16)
> +
> +#define IPQ_PWM_CFG_REG1 4 /*ENABLE UPDATE PWM_PRE_DIV*/
> +#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;
> +	struct regmap *regmap;
> +	u32 regmap_off;
> +};
> +
> +static struct ipq_pwm_chip *to_ipq_pwm_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 reg)
> +{
> +	struct ipq_pwm_chip *ipq_chip = to_ipq_pwm_chip(pwm->chip);
> +	unsigned int off = ipq_chip->regmap_off + 8 * pwm->hwpwm + reg;
> +	unsigned int val;
> +
> +	regmap_read(ipq_chip->regmap, off, &val);
> +
> +	return val;
> +}
> +
> +static void ipq_pwm_reg_write(struct pwm_device *pwm, unsigned reg,
> +		unsigned val)
> +{
> +	struct ipq_pwm_chip *ipq_chip = to_ipq_pwm_chip(pwm->chip);
> +	unsigned int off = ipq_chip->regmap_off + 8 * pwm->hwpwm + reg;
> +
> +	regmap_write(ipq_chip->regmap, off, val);
> +}
> +
> +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_CFG_REG0, val);
> +
> +	val = FIELD_PREP(IPQ_PWM_REG1_PRE_DIV, pre_div);
> +	ipq_pwm_reg_write(pwm, IPQ_PWM_CFG_REG1, val);
> +
> +	/* Enable 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_CFG_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 = to_ipq_pwm_chip(chip);
> +	unsigned long freq;
> +	unsigned int pre_div, pwm_div, best_pre_div, best_pwm_div;
> +	long long diff;
> +	unsigned long rate = clk_get_rate(ipq_chip->clk);
> +	unsigned long min_diff = rate;
> +	u64 period_ns, duty_ns;
> +
> +	if (state->polarity != PWM_POLARITY_NORMAL)
> +		return -EINVAL;
> +
> +	if (state->period < div64_u64(NSEC_PER_SEC, rate))
> +		return -ERANGE;
> +
> +	period_ns = min(state->period, IPQ_PWM_MAX_PERIOD_NS);
> +	duty_ns = min(state->duty_cycle, period_ns);
> +
> +	/* freq in Hz for period in nano second */
> +	freq = div64_u64(NSEC_PER_SEC, period_ns);
> +	best_pre_div = IPQ_PWM_MAX_DIV;
> +	best_pwm_div = IPQ_PWM_MAX_DIV;
> +	/* Initial pre_div value such that pwm_div < IPQ_PWM_MAX_DIV */
> +	pre_div = DIV64_U64_ROUND_UP(period_ns * rate,
> +			(u64)NSEC_PER_SEC * (IPQ_PWM_MAX_DIV + 1));
> +
> +	for (; pre_div <= IPQ_PWM_MAX_DIV; pre_div++) {
> +		pwm_div = DIV64_U64_ROUND_UP(period_ns * rate,
> +				(u64)NSEC_PER_SEC * (pre_div + 1));
> +		pwm_div--;
> +
> +		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;
> +
> +		diff = ((uint64_t)freq * (pre_div + 1) * (pwm_div + 1))
> +			- (uint64_t)rate;
> +
> +		if (diff < 0) /* period larger than requested */
> +			continue;
> +		if (diff == 0) { /* bingo */
> +			best_pre_div = pre_div;
> +			best_pwm_div = pwm_div;
> +			break;
> +		}
> +		if (diff < min_diff) {
> +			min_diff = diff;
> +			best_pre_div = pre_div;
> +			best_pwm_div = pwm_div;
> +		}
> +	}
> +
> +	/* 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 = to_ipq_pwm_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_CFG_REG0);
> +	reg1 = ipq_pwm_reg_read(pwm, IPQ_PWM_CFG_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(effective_div * NSEC_PER_SEC, rate);
> +
> +	hi_div = hi_dur * (pre_div + 1);
> +	state->duty_cycle = div64_u64(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->regmap = syscon_node_to_regmap(dev->parent->of_node);
> +	if (IS_ERR(pwm->regmap))
> +		return dev_err_probe(dev, PTR_ERR(pwm->regmap),
> +				"regs map failed");
> +
> +	ret = of_property_read_u32(dev->of_node, "offset", &pwm->regmap_off);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "error reading 'offset'");
> +
> +	pwm->clk = devm_clk_get(dev, "core");

You only have a single clock, so passing NULL for the identifier would
do the trick...

> +	if (IS_ERR(pwm->clk))
> +		return dev_err_probe(dev, PTR_ERR(pwm->clk),
> +				"failed to get core clock");
> +
> +	ret = clk_prepare_enable(pwm->clk);

Not sure if Uwe asked you this already, but do you need to clock the
supply even when the PWM isn't enabled?

> +	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);

Depending on above answer you may or may not have the need to ensure the
ordering of clk_disable_unprepare() in the remove function.

Otherwise devm_pwmchip_add() would be nice here.

> +	if (ret < 0) {
> +		dev_err_probe(dev, ret, "pwmchip_add() failed\n");
> +		clk_disable_unprepare(pwm->clk);
> +		return ret;

pwmchip_add() returns 0 or -errno, so you could skip this and do return
ret; below.

> +	}
> +
> +	return 0;
> +}
> +
> +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");
> -- 
> 2.30.2
> 

Re: [PATCH v6 3/4] dt-bindings: pwm: add IPQ6018 binding

[Baruch Siach]

Hi Bjorn,

On Sun, Jul 25 2021, Bjorn Andersson wrote:
> On Thu 22 Jul 05:01 CDT 2021, Baruch Siach wrote:
>> +  clocks:
>> +    maxItems: 1
>> +
>> +  clock-names:
>> +    const: core
>
> With a single clock, it's nice to skip the -names.

I find it nicer and better for forward compatibility with hardware
variants the might introduce more clocks.

Are there any downsides to -names?

Thanks,
baruch

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

Re: [PATCH v6 2/4] pwm: driver for qualcomm ipq6018 pwm block

[Baruch Siach]

Hi Bjorn,

On Sun, Jul 25 2021, Bjorn Andersson wrote:
> On Thu 22 Jul 05:01 CDT 2021, Baruch Siach wrote:
>> +	if (IS_ERR(pwm->clk))
>> +		return dev_err_probe(dev, PTR_ERR(pwm->clk),
>> +				"failed to get core clock");
>> +
>> +	ret = clk_prepare_enable(pwm->clk);
>
> Not sure if Uwe asked you this already, but do you need to clock the
> supply even when the PWM isn't enabled?

I guess not. However, tracking clock enable/disable per PWM signal
complicates the code. We'd need to balance enables with matching
disables in the .remove callback. I'd prefer to leave that as room for
future optimization.

>> +	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);
>
> Depending on above answer you may or may not have the need to ensure the
> ordering of clk_disable_unprepare() in the remove function.

According to Uwe pwmchip_remove() must precede clock disable:

  https://lore.kernel.org/linux-arm-msm/20210714201839.kfyqcyvowekc4ejs@pengutronix.de/

How is that related to per PWM signal clock handling?

> Otherwise devm_pwmchip_add() would be nice here.

Thanks,
baruch

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

Re: [PATCH v6 3/4] dt-bindings: pwm: add IPQ6018 binding

[Bjorn Andersson]

On Sun 25 Jul 21:08 PDT 2021, Baruch Siach wrote:

> Hi Bjorn,
> 
> On Sun, Jul 25 2021, Bjorn Andersson wrote:
> > On Thu 22 Jul 05:01 CDT 2021, Baruch Siach wrote:
> >> +  clocks:
> >> +    maxItems: 1
> >> +
> >> +  clock-names:
> >> +    const: core
> >
> > With a single clock, it's nice to skip the -names.
> 
> I find it nicer and better for forward compatibility with hardware
> variants the might introduce more clocks.
> 

Do you foresee any need for forward compatibility? What other clocks
would this binding have to refer to?

That said, you'd achieve the same forward compatibility by just
making sure that the current clock is the first on in the amended
binding (which you have to do with or without -names).

> Are there any downsides to -names?
> 

Look at the number of places in a typical dts that we could have added
clock-names, reg-names, interrupt-names, power-domain-names etc for a
single cell.

I do find it beneficial to keep things cleaner and sticking with the
design of "single resource has no -names".

Regards,
Bjorn

Re: [PATCH v6 3/4] dt-bindings: pwm: add IPQ6018 binding

[Rob Herring]

On Sun, Jul 25, 2021 at 12:27 PM Bjorn Andersson
<bjorn.andersson@linaro.org> wrote:
>
> On Thu 22 Jul 05:01 CDT 2021, Baruch Siach wrote:
>
> > DT binding for the PWM block in Qualcomm IPQ6018 SoC.
> >
> > Signed-off-by: Baruch Siach <baruch@tkos.co.il>
> > ---
> > v6:
> >
> >   Device node is child of TCSR; remove phandle (Rob Herring)
> >
> >   Add assigned-clocks/assigned-clock-rates (Uwe Kleine-König)
> >
> > v5: Use qcom,pwm-regs for phandle instead of direct regs (Bjorn
> >     Andersson, Kathiravan T)
> >
> > v4: Update the binding example node as well (Rob Herring's bot)
> >
> > v3: s/qcom,pwm-ipq6018/qcom,ipq6018-pwm/ (Rob Herring)
> >
> > v2: Make #pwm-cells const (Rob Herring)
> > ---
> >  .../devicetree/bindings/pwm/ipq-pwm.yaml      | 69 +++++++++++++++++++
> >  1 file changed, 69 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..ee2bb03a1223
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/pwm/ipq-pwm.yaml
> > @@ -0,0 +1,69 @@
> > +# 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":
> > +    const: 2
> > +
> > +  compatible:
> > +    const: qcom,ipq6018-pwm
> > +
> > +  offset:
> > +    description: |
>
> '|' maintains the formatting of the text, you don't need that.
>
> > +      Offset of PWM register in the TCSR block.
> > +    maxItems: 1
> > +
> > +  clocks:
> > +    maxItems: 1
> > +
> > +  clock-names:
> > +    const: core
>
> With a single clock, it's nice to skip the -names.
>
> > +
> > +  assigned-clocks:
> > +    maxItems: 1
> > +
> > +  assigned-clock-rates:
> > +    maxItems: 1
>
> These (assigned-*) are generic properties that may be used on a lot of
> nodes, should they really be part of the individual binding, Rob?

They are allowed on any node with 'clocks', so you don't need them.
However, if you know there's 1 entry only, then I'd keep that. Or was
'maxItems: 1' just copied because I see that alot.

Rob