[PATCH v6 0/2] pwm: visconti: Add Toshiba Visconti SoC PWM support

[PATCH v6 0/2] pwm: visconti: Add Toshiba Visconti SoC PWM support

[Nobuhiro Iwamatsu]

Hi,

This series is the PWM driver for Toshiba's ARM SoC, Visconti[0].
This provides DT binding documentation and device driver.

[0]: https://toshiba.semicon-storage.com/ap-en/semiconductor/product/image-recognition-processors-visconti.html

Updates:

  dt-bindings: pwm: Add bindings for Toshiba Visconti PWM Controller
    v5 -> v6:
      - No update.
    v4 -> v5:
      - No update.
    v3 -> v4:
      - No update.
    v2 -> v3:
      - Change compatible to toshiba,visconti-pwm
      - Change filename to toshiba,visconti-pwm.yaml.
      - Add Reviewed-by tag from Rob.
    v1 -> v2:
      - Change SPDX-License-Identifier to GPL-2.0-only OR BSD-2-Clause.
      - Set compatible toshiba,pwm-visconti only.
      - Drop unnecessary comments.

  pwm: visconti: Add Toshiba Visconti SoC PWM support
    v5 -> v6:
     - Update year in copyright.
     - Update limitations.
     - Fix coding style, used braces for both branches.
    v4 -> v5:
      - Droped checking PIPGM_PCSR from visconti_pwm_get_state.
      - Changed from to_visconti_chip to visconti_pwm_from_chip.
      - Removed pwmchip_remove return value management.
      - Add limitations of this device.
      - Add 'state->enabled = true' to visconti_pwm_get_state().
    v3 -> v4:
      - Sorted alphabetically include files.
      - Changed container_of to using static inline functions.
      - Dropped unnecessary dev_dbg().
      - Drop Initialization of chip.base.
      - Drop commnet "period too small".
      - Rebased for-next. 
    v2 -> v3:
      - Change compatible to toshiba,visconti-pwm.
      - Fix MODULE_ALIAS to platform:pwm-visconti, again.
      - Align continuation line to the opening parenthesis.
      - Rewrite the contents of visconti_pwm_apply() based on the contents suggested by Uwe.
    v1 -> v2:
      - Change SPDX-License-Identifier to GPL-2.0-only.
      - Add prefix for the register defines.
      - Drop struct device from struct visconti_pwm_chip.
      - Use '>>' instead of '/'.
      - Drop error message by devm_platform_ioremap_resource().
      - Use dev_err_probe instead of dev_err.
      - Change dev_info to dev_dbg.
      - Remove some empty lines.
      - Fix MODULE_ALIAS to platform:pwm-visconti.
      - Add .get_state() function.
      - Use the author name and email address to MODULE_AUTHOR.
      - Add more comment to function of the hardware.
      - Support .get_status() function.
      - Use NSEC_PER_USEC instead of 1000.
      - Alphabetically sorted for Makefile and Kconfig.
      - Added check for set value in visconti_pwm_apply().

Nobuhiro Iwamatsu (2):
  dt-bindings: pwm: Add bindings for Toshiba Visconti PWM Controller
  pwm: visconti: Add Toshiba Visconti SoC PWM support

 .../bindings/pwm/toshiba,pwm-visconti.yaml    |  43 ++++
 drivers/pwm/Kconfig                           |   9 +
 drivers/pwm/Makefile                          |   1 +
 drivers/pwm/pwm-visconti.c                    | 189 ++++++++++++++++++
 4 files changed, 242 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/toshiba,pwm-visconti.yaml
 create mode 100644 drivers/pwm/pwm-visconti.c

-- 
2.30.0.rc2

[PATCH v6 0/2] pwm: visconti: Add Toshiba Visconti SoC PWM support

[Nobuhiro Iwamatsu]

Hi,

This series is the PWM driver for Toshiba's ARM SoC, Visconti[0].
This provides DT binding documentation and device driver.

[0]: https://toshiba.semicon-storage.com/ap-en/semiconductor/product/image-recognition-processors-visconti.html

Updates:

  dt-bindings: pwm: Add bindings for Toshiba Visconti PWM Controller
    v5 -> v6:
      - No update.
    v4 -> v5:
      - No update.
    v3 -> v4:
      - No update.
    v2 -> v3:
      - Change compatible to toshiba,visconti-pwm
      - Change filename to toshiba,visconti-pwm.yaml.
      - Add Reviewed-by tag from Rob.
    v1 -> v2:
      - Change SPDX-License-Identifier to GPL-2.0-only OR BSD-2-Clause.
      - Set compatible toshiba,pwm-visconti only.
      - Drop unnecessary comments.

  pwm: visconti: Add Toshiba Visconti SoC PWM support
    v5 -> v6:
     - Update year in copyright.
     - Update limitations.
     - Fix coding style, used braces for both branches.
    v4 -> v5:
      - Droped checking PIPGM_PCSR from visconti_pwm_get_state.
      - Changed from to_visconti_chip to visconti_pwm_from_chip.
      - Removed pwmchip_remove return value management.
      - Add limitations of this device.
      - Add 'state->enabled = true' to visconti_pwm_get_state().
    v3 -> v4:
      - Sorted alphabetically include files.
      - Changed container_of to using static inline functions.
      - Dropped unnecessary dev_dbg().
      - Drop Initialization of chip.base.
      - Drop commnet "period too small".
      - Rebased for-next. 
    v2 -> v3:
      - Change compatible to toshiba,visconti-pwm.
      - Fix MODULE_ALIAS to platform:pwm-visconti, again.
      - Align continuation line to the opening parenthesis.
      - Rewrite the contents of visconti_pwm_apply() based on the contents suggested by Uwe.
    v1 -> v2:
      - Change SPDX-License-Identifier to GPL-2.0-only.
      - Add prefix for the register defines.
      - Drop struct device from struct visconti_pwm_chip.
      - Use '>>' instead of '/'.
      - Drop error message by devm_platform_ioremap_resource().
      - Use dev_err_probe instead of dev_err.
      - Change dev_info to dev_dbg.
      - Remove some empty lines.
      - Fix MODULE_ALIAS to platform:pwm-visconti.
      - Add .get_state() function.
      - Use the author name and email address to MODULE_AUTHOR.
      - Add more comment to function of the hardware.
      - Support .get_status() function.
      - Use NSEC_PER_USEC instead of 1000.
      - Alphabetically sorted for Makefile and Kconfig.
      - Added check for set value in visconti_pwm_apply().

Nobuhiro Iwamatsu (2):
  dt-bindings: pwm: Add bindings for Toshiba Visconti PWM Controller
  pwm: visconti: Add Toshiba Visconti SoC PWM support

 .../bindings/pwm/toshiba,pwm-visconti.yaml    |  43 ++++
 drivers/pwm/Kconfig                           |   9 +
 drivers/pwm/Makefile                          |   1 +
 drivers/pwm/pwm-visconti.c                    | 189 ++++++++++++++++++
 4 files changed, 242 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/toshiba,pwm-visconti.yaml
 create mode 100644 drivers/pwm/pwm-visconti.c

-- 
2.30.0.rc2


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH v6 1/2] dt-bindings: pwm: Add bindings for Toshiba Visconti PWM Controller

[Nobuhiro Iwamatsu]

Add bindings for the Toshiba Visconti PWM Controller.

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
Reviewed-by: Rob Herring <robh@kernel.org>
---
 .../bindings/pwm/toshiba,pwm-visconti.yaml    | 43 +++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/toshiba,pwm-visconti.yaml

diff --git a/Documentation/devicetree/bindings/pwm/toshiba,pwm-visconti.yaml b/Documentation/devicetree/bindings/pwm/toshiba,pwm-visconti.yaml
new file mode 100644
index 000000000000..d350f5edfb67
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/toshiba,pwm-visconti.yaml
@@ -0,0 +1,43 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pwm/toshiba,pwm-visconti.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Toshiba Visconti PWM Controller
+
+maintainers:
+  - Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
+
+properties:
+  compatible:
+    items:
+      - const: toshiba,visconti-pwm
+
+  reg:
+    maxItems: 1
+
+  '#pwm-cells':
+    const: 2
+
+required:
+  - compatible
+  - reg
+  - '#pwm-cells'
+
+additionalProperties: false
+
+examples:
+  - |
+    soc {
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        pwm: pwm@241c0000 {
+            compatible = "toshiba,visconti-pwm";
+            reg = <0 0x241c0000 0 0x1000>;
+            pinctrl-names = "default";
+            pinctrl-0 = <&pwm_mux>;
+            #pwm-cells = <2>;
+        };
+    };
-- 
2.30.0.rc2

[PATCH v6 1/2] dt-bindings: pwm: Add bindings for Toshiba Visconti PWM Controller

[Nobuhiro Iwamatsu]

Add bindings for the Toshiba Visconti PWM Controller.

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
Reviewed-by: Rob Herring <robh@kernel.org>
---
 .../bindings/pwm/toshiba,pwm-visconti.yaml    | 43 +++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/toshiba,pwm-visconti.yaml

diff --git a/Documentation/devicetree/bindings/pwm/toshiba,pwm-visconti.yaml b/Documentation/devicetree/bindings/pwm/toshiba,pwm-visconti.yaml
new file mode 100644
index 000000000000..d350f5edfb67
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/toshiba,pwm-visconti.yaml
@@ -0,0 +1,43 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pwm/toshiba,pwm-visconti.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Toshiba Visconti PWM Controller
+
+maintainers:
+  - Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
+
+properties:
+  compatible:
+    items:
+      - const: toshiba,visconti-pwm
+
+  reg:
+    maxItems: 1
+
+  '#pwm-cells':
+    const: 2
+
+required:
+  - compatible
+  - reg
+  - '#pwm-cells'
+
+additionalProperties: false
+
+examples:
+  - |
+    soc {
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        pwm: pwm@241c0000 {
+            compatible = "toshiba,visconti-pwm";
+            reg = <0 0x241c0000 0 0x1000>;
+            pinctrl-names = "default";
+            pinctrl-0 = <&pwm_mux>;
+            #pwm-cells = <2>;
+        };
+    };
-- 
2.30.0.rc2


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH v6 2/2] pwm: visconti: Add Toshiba Visconti SoC PWM support

[Nobuhiro Iwamatsu]

Add driver for the PWM controller on Toshiba Visconti ARM SoC.

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
---
 drivers/pwm/Kconfig        |   9 ++
 drivers/pwm/Makefile       |   1 +
 drivers/pwm/pwm-visconti.c | 189 +++++++++++++++++++++++++++++++++++++
 3 files changed, 199 insertions(+)
 create mode 100644 drivers/pwm/pwm-visconti.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 9a4f66ae8070..8ae68d6203fb 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -601,6 +601,15 @@ config PWM_TWL_LED
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-twl-led.
 
+config PWM_VISCONTI
+	tristate "Toshiba Visconti PWM support"
+	depends on ARCH_VISCONTI || COMPILE_TEST
+	help
+	  PWM Subsystem driver support for Toshiba Visconti SoCs.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-visconti.
+
 config PWM_VT8500
 	tristate "vt8500 PWM support"
 	depends on ARCH_VT8500 || COMPILE_TEST
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 6374d3b1d6f3..d43b1e17e8e1 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -56,4 +56,5 @@ obj-$(CONFIG_PWM_TIECAP)	+= pwm-tiecap.o
 obj-$(CONFIG_PWM_TIEHRPWM)	+= pwm-tiehrpwm.o
 obj-$(CONFIG_PWM_TWL)		+= pwm-twl.o
 obj-$(CONFIG_PWM_TWL_LED)	+= pwm-twl-led.o
+obj-$(CONFIG_PWM_VISCONTI)	+= pwm-visconti.o
 obj-$(CONFIG_PWM_VT8500)	+= pwm-vt8500.o
diff --git a/drivers/pwm/pwm-visconti.c b/drivers/pwm/pwm-visconti.c
new file mode 100644
index 000000000000..beecadda566a
--- /dev/null
+++ b/drivers/pwm/pwm-visconti.c
@@ -0,0 +1,189 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Toshiba Visconti pulse-width-modulation controller driver
+ *
+ * Copyright (c) 2020 - 2021 TOSHIBA CORPORATION
+ * Copyright (c) 2020 - 2021 Toshiba Electronic Devices & Storage Corporation
+ *
+ * Authors: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
+ *
+ * Limitations:
+ * - The fixed input clock is running at 1 MHz and is divided by either 1,
+ *   2, 4 or 8.
+ * - When the settings of the PWM are modified, the new values are shadowed
+ *   in hardware until the PIPGM_PCSR register is written and the currently
+ *   running period is completed. This way the hardware switches atomically
+ *   from the old setting to the new.
+ * - Disabling the hardware completes the currently running period and keeps
+ *   the output at low level at all times.
+ */
+
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+
+#define PIPGM_PCSR(ch) (0x400 + 4 * (ch))
+#define PIPGM_PDUT(ch) (0x420 + 4 * (ch))
+#define PIPGM_PWMC(ch) (0x440 + 4 * (ch))
+
+#define PIPGM_PWMC_PWMACT		BIT(5)
+#define PIPGM_PWMC_CLK_MASK		GENMASK(1, 0)
+#define PIPGM_PWMC_POLARITY_MASK	GENMASK(5, 5)
+
+struct visconti_pwm_chip {
+	struct pwm_chip chip;
+	void __iomem *base;
+};
+
+static inline struct visconti_pwm_chip *visconti_pwm_from_chip(struct pwm_chip *chip)
+{
+	return container_of(chip, struct visconti_pwm_chip, chip);
+}
+
+static int visconti_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			      const struct pwm_state *state)
+{
+	struct visconti_pwm_chip *priv = visconti_pwm_from_chip(chip);
+	u32 period, duty_cycle, pwmc0;
+
+	if (!state->enabled) {
+		writel(0, priv->base + PIPGM_PCSR(pwm->hwpwm));
+		return 0;
+	}
+
+	/*
+	 * The biggest period the hardware can provide is
+	 *	(0xffff << 3) * 1000 ns
+	 * This value fits easily in an u32, so simplify the maths by
+	 * capping the values to 32 bit integers.
+	 */
+	if (state->period > (0xffff << 3) * 1000)
+		period = (0xffff << 3) * 1000;
+	else
+		period = state->period;
+
+	if (state->duty_cycle > period)
+		duty_cycle = period;
+	else
+		duty_cycle = state->duty_cycle;
+
+	/*
+	 * The input clock runs fixed at 1 MHz, so we have only
+	 * microsecond resolution and so can divide by
+	 * NSEC_PER_SEC / CLKFREQ = 1000 without loosing precision.
+	 */
+	period /= 1000;
+	duty_cycle /= 1000;
+
+	if (!period)
+		return -ERANGE;
+
+	/*
+	 * PWMC controls a divider that divides the input clk by a
+	 * power of two between 1 and 8. As a smaller divider yields
+	 * higher precision, pick the smallest possible one.
+	 */
+	if (period > 0xffff) {
+		pwmc0 = ilog2(period >> 16);
+		BUG_ON(pwmc0 > 3);
+	} else {
+		pwmc0 = 0;
+	}
+
+	period >>= pwmc0;
+	duty_cycle >>= pwmc0;
+
+	if (state->polarity == PWM_POLARITY_INVERSED)
+		pwmc0 |= PIPGM_PWMC_PWMACT;
+	writel(pwmc0, priv->base + PIPGM_PWMC(pwm->hwpwm));
+	writel(duty_cycle, priv->base + PIPGM_PDUT(pwm->hwpwm));
+	writel(period, priv->base + PIPGM_PCSR(pwm->hwpwm));
+
+	return 0;
+}
+
+static void visconti_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+				   struct pwm_state *state)
+{
+	struct visconti_pwm_chip *priv = visconti_pwm_from_chip(chip);
+	u32 period, duty, pwmc0, pwmc0_clk;
+
+	period = readl(priv->base + PIPGM_PCSR(pwm->hwpwm));
+	duty = readl(priv->base + PIPGM_PDUT(pwm->hwpwm));
+	pwmc0 = readl(priv->base + PIPGM_PWMC(pwm->hwpwm));
+	pwmc0_clk = pwmc0 & PIPGM_PWMC_CLK_MASK;
+
+	state->period = (period << pwmc0_clk) * NSEC_PER_USEC;
+	state->duty_cycle = (duty << pwmc0_clk) * NSEC_PER_USEC;
+	if (pwmc0 & PIPGM_PWMC_POLARITY_MASK)
+		state->polarity = PWM_POLARITY_INVERSED;
+	else
+		state->polarity = PWM_POLARITY_NORMAL;
+
+	state->enabled = true;
+}
+
+static const struct pwm_ops visconti_pwm_ops = {
+	.apply = visconti_pwm_apply,
+	.get_state = visconti_pwm_get_state,
+	.owner = THIS_MODULE,
+};
+
+static int visconti_pwm_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct visconti_pwm_chip *priv;
+	int ret;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(priv->base))
+		return PTR_ERR(priv->base);
+
+	platform_set_drvdata(pdev, priv);
+
+	priv->chip.dev = dev;
+	priv->chip.ops = &visconti_pwm_ops;
+	priv->chip.npwm = 4;
+
+	ret = pwmchip_add(&priv->chip);
+	if (ret < 0)
+		return dev_err_probe(&pdev->dev, ret, "Cannot register visconti PWM\n");
+
+	return 0;
+}
+
+static int visconti_pwm_remove(struct platform_device *pdev)
+{
+	struct visconti_pwm_chip *priv = platform_get_drvdata(pdev);
+
+	pwmchip_remove(&priv->chip);
+
+	return 0;
+}
+
+static const struct of_device_id visconti_pwm_of_match[] = {
+	{ .compatible = "toshiba,visconti-pwm", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, visconti_pwm_of_match);
+
+static struct platform_driver visconti_pwm_driver = {
+	.driver = {
+		.name = "pwm-visconti",
+		.of_match_table = visconti_pwm_of_match,
+	},
+	.probe = visconti_pwm_probe,
+	.remove = visconti_pwm_remove,
+};
+module_platform_driver(visconti_pwm_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>");
+MODULE_ALIAS("platform:pwm-visconti");
-- 
2.30.0.rc2

[PATCH v6 2/2] pwm: visconti: Add Toshiba Visconti SoC PWM support

[Nobuhiro Iwamatsu]

Add driver for the PWM controller on Toshiba Visconti ARM SoC.

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
---
 drivers/pwm/Kconfig        |   9 ++
 drivers/pwm/Makefile       |   1 +
 drivers/pwm/pwm-visconti.c | 189 +++++++++++++++++++++++++++++++++++++
 3 files changed, 199 insertions(+)
 create mode 100644 drivers/pwm/pwm-visconti.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 9a4f66ae8070..8ae68d6203fb 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -601,6 +601,15 @@ config PWM_TWL_LED
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-twl-led.
 
+config PWM_VISCONTI
+	tristate "Toshiba Visconti PWM support"
+	depends on ARCH_VISCONTI || COMPILE_TEST
+	help
+	  PWM Subsystem driver support for Toshiba Visconti SoCs.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-visconti.
+
 config PWM_VT8500
 	tristate "vt8500 PWM support"
 	depends on ARCH_VT8500 || COMPILE_TEST
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 6374d3b1d6f3..d43b1e17e8e1 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -56,4 +56,5 @@ obj-$(CONFIG_PWM_TIECAP)	+= pwm-tiecap.o
 obj-$(CONFIG_PWM_TIEHRPWM)	+= pwm-tiehrpwm.o
 obj-$(CONFIG_PWM_TWL)		+= pwm-twl.o
 obj-$(CONFIG_PWM_TWL_LED)	+= pwm-twl-led.o
+obj-$(CONFIG_PWM_VISCONTI)	+= pwm-visconti.o
 obj-$(CONFIG_PWM_VT8500)	+= pwm-vt8500.o
diff --git a/drivers/pwm/pwm-visconti.c b/drivers/pwm/pwm-visconti.c
new file mode 100644
index 000000000000..beecadda566a
--- /dev/null
+++ b/drivers/pwm/pwm-visconti.c
@@ -0,0 +1,189 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Toshiba Visconti pulse-width-modulation controller driver
+ *
+ * Copyright (c) 2020 - 2021 TOSHIBA CORPORATION
+ * Copyright (c) 2020 - 2021 Toshiba Electronic Devices & Storage Corporation
+ *
+ * Authors: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
+ *
+ * Limitations:
+ * - The fixed input clock is running at 1 MHz and is divided by either 1,
+ *   2, 4 or 8.
+ * - When the settings of the PWM are modified, the new values are shadowed
+ *   in hardware until the PIPGM_PCSR register is written and the currently
+ *   running period is completed. This way the hardware switches atomically
+ *   from the old setting to the new.
+ * - Disabling the hardware completes the currently running period and keeps
+ *   the output at low level at all times.
+ */
+
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+
+#define PIPGM_PCSR(ch) (0x400 + 4 * (ch))
+#define PIPGM_PDUT(ch) (0x420 + 4 * (ch))
+#define PIPGM_PWMC(ch) (0x440 + 4 * (ch))
+
+#define PIPGM_PWMC_PWMACT		BIT(5)
+#define PIPGM_PWMC_CLK_MASK		GENMASK(1, 0)
+#define PIPGM_PWMC_POLARITY_MASK	GENMASK(5, 5)
+
+struct visconti_pwm_chip {
+	struct pwm_chip chip;
+	void __iomem *base;
+};
+
+static inline struct visconti_pwm_chip *visconti_pwm_from_chip(struct pwm_chip *chip)
+{
+	return container_of(chip, struct visconti_pwm_chip, chip);
+}
+
+static int visconti_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			      const struct pwm_state *state)
+{
+	struct visconti_pwm_chip *priv = visconti_pwm_from_chip(chip);
+	u32 period, duty_cycle, pwmc0;
+
+	if (!state->enabled) {
+		writel(0, priv->base + PIPGM_PCSR(pwm->hwpwm));
+		return 0;
+	}
+
+	/*
+	 * The biggest period the hardware can provide is
+	 *	(0xffff << 3) * 1000 ns
+	 * This value fits easily in an u32, so simplify the maths by
+	 * capping the values to 32 bit integers.
+	 */
+	if (state->period > (0xffff << 3) * 1000)
+		period = (0xffff << 3) * 1000;
+	else
+		period = state->period;
+
+	if (state->duty_cycle > period)
+		duty_cycle = period;
+	else
+		duty_cycle = state->duty_cycle;
+
+	/*
+	 * The input clock runs fixed at 1 MHz, so we have only
+	 * microsecond resolution and so can divide by
+	 * NSEC_PER_SEC / CLKFREQ = 1000 without loosing precision.
+	 */
+	period /= 1000;
+	duty_cycle /= 1000;
+
+	if (!period)
+		return -ERANGE;
+
+	/*
+	 * PWMC controls a divider that divides the input clk by a
+	 * power of two between 1 and 8. As a smaller divider yields
+	 * higher precision, pick the smallest possible one.
+	 */
+	if (period > 0xffff) {
+		pwmc0 = ilog2(period >> 16);
+		BUG_ON(pwmc0 > 3);
+	} else {
+		pwmc0 = 0;
+	}
+
+	period >>= pwmc0;
+	duty_cycle >>= pwmc0;
+
+	if (state->polarity == PWM_POLARITY_INVERSED)
+		pwmc0 |= PIPGM_PWMC_PWMACT;
+	writel(pwmc0, priv->base + PIPGM_PWMC(pwm->hwpwm));
+	writel(duty_cycle, priv->base + PIPGM_PDUT(pwm->hwpwm));
+	writel(period, priv->base + PIPGM_PCSR(pwm->hwpwm));
+
+	return 0;
+}
+
+static void visconti_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+				   struct pwm_state *state)
+{
+	struct visconti_pwm_chip *priv = visconti_pwm_from_chip(chip);
+	u32 period, duty, pwmc0, pwmc0_clk;
+
+	period = readl(priv->base + PIPGM_PCSR(pwm->hwpwm));
+	duty = readl(priv->base + PIPGM_PDUT(pwm->hwpwm));
+	pwmc0 = readl(priv->base + PIPGM_PWMC(pwm->hwpwm));
+	pwmc0_clk = pwmc0 & PIPGM_PWMC_CLK_MASK;
+
+	state->period = (period << pwmc0_clk) * NSEC_PER_USEC;
+	state->duty_cycle = (duty << pwmc0_clk) * NSEC_PER_USEC;
+	if (pwmc0 & PIPGM_PWMC_POLARITY_MASK)
+		state->polarity = PWM_POLARITY_INVERSED;
+	else
+		state->polarity = PWM_POLARITY_NORMAL;
+
+	state->enabled = true;
+}
+
+static const struct pwm_ops visconti_pwm_ops = {
+	.apply = visconti_pwm_apply,
+	.get_state = visconti_pwm_get_state,
+	.owner = THIS_MODULE,
+};
+
+static int visconti_pwm_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct visconti_pwm_chip *priv;
+	int ret;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(priv->base))
+		return PTR_ERR(priv->base);
+
+	platform_set_drvdata(pdev, priv);
+
+	priv->chip.dev = dev;
+	priv->chip.ops = &visconti_pwm_ops;
+	priv->chip.npwm = 4;
+
+	ret = pwmchip_add(&priv->chip);
+	if (ret < 0)
+		return dev_err_probe(&pdev->dev, ret, "Cannot register visconti PWM\n");
+
+	return 0;
+}
+
+static int visconti_pwm_remove(struct platform_device *pdev)
+{
+	struct visconti_pwm_chip *priv = platform_get_drvdata(pdev);
+
+	pwmchip_remove(&priv->chip);
+
+	return 0;
+}
+
+static const struct of_device_id visconti_pwm_of_match[] = {
+	{ .compatible = "toshiba,visconti-pwm", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, visconti_pwm_of_match);
+
+static struct platform_driver visconti_pwm_driver = {
+	.driver = {
+		.name = "pwm-visconti",
+		.of_match_table = visconti_pwm_of_match,
+	},
+	.probe = visconti_pwm_probe,
+	.remove = visconti_pwm_remove,
+};
+module_platform_driver(visconti_pwm_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>");
+MODULE_ALIAS("platform:pwm-visconti");
-- 
2.30.0.rc2


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Re: [PATCH v6 2/2] pwm: visconti: Add Toshiba Visconti SoC PWM support

[Uwe Kleine-König]

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On Mon, Apr 19, 2021 at 09:00:07AM +0900, Nobuhiro Iwamatsu wrote:
> Add driver for the PWM controller on Toshiba Visconti ARM SoC.
> 
> Signed-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>

Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Thanks for your endurance to improve the driver
Uwe

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

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Re: [PATCH v6 2/2] pwm: visconti: Add Toshiba Visconti SoC PWM support

[Uwe Kleine-König]

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On Mon, Apr 19, 2021 at 09:00:07AM +0900, Nobuhiro Iwamatsu wrote:
> Add driver for the PWM controller on Toshiba Visconti ARM SoC.
> 
> Signed-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>

Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Thanks for your endurance to improve the driver
Uwe

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

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Re: [PATCH v6 0/2] pwm: visconti: Add Toshiba Visconti SoC PWM support

[Thierry Reding]

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On Mon, Apr 19, 2021 at 09:00:05AM +0900, Nobuhiro Iwamatsu wrote:
> Hi,
> 
> This series is the PWM driver for Toshiba's ARM SoC, Visconti[0].
> This provides DT binding documentation and device driver.
> 
> [0]: https://toshiba.semicon-storage.com/ap-en/semiconductor/product/image-recognition-processors-visconti.html
> 
> Updates:
> 
>   dt-bindings: pwm: Add bindings for Toshiba Visconti PWM Controller
>     v5 -> v6:
>       - No update.
>     v4 -> v5:
>       - No update.
>     v3 -> v4:
>       - No update.
>     v2 -> v3:
>       - Change compatible to toshiba,visconti-pwm
>       - Change filename to toshiba,visconti-pwm.yaml.
>       - Add Reviewed-by tag from Rob.
>     v1 -> v2:
>       - Change SPDX-License-Identifier to GPL-2.0-only OR BSD-2-Clause.
>       - Set compatible toshiba,pwm-visconti only.
>       - Drop unnecessary comments.
> 
>   pwm: visconti: Add Toshiba Visconti SoC PWM support
>     v5 -> v6:
>      - Update year in copyright.
>      - Update limitations.
>      - Fix coding style, used braces for both branches.
>     v4 -> v5:
>       - Droped checking PIPGM_PCSR from visconti_pwm_get_state.
>       - Changed from to_visconti_chip to visconti_pwm_from_chip.
>       - Removed pwmchip_remove return value management.
>       - Add limitations of this device.
>       - Add 'state->enabled = true' to visconti_pwm_get_state().
>     v3 -> v4:
>       - Sorted alphabetically include files.
>       - Changed container_of to using static inline functions.
>       - Dropped unnecessary dev_dbg().
>       - Drop Initialization of chip.base.
>       - Drop commnet "period too small".
>       - Rebased for-next. 
>     v2 -> v3:
>       - Change compatible to toshiba,visconti-pwm.
>       - Fix MODULE_ALIAS to platform:pwm-visconti, again.
>       - Align continuation line to the opening parenthesis.
>       - Rewrite the contents of visconti_pwm_apply() based on the contents suggested by Uwe.
>     v1 -> v2:
>       - Change SPDX-License-Identifier to GPL-2.0-only.
>       - Add prefix for the register defines.
>       - Drop struct device from struct visconti_pwm_chip.
>       - Use '>>' instead of '/'.
>       - Drop error message by devm_platform_ioremap_resource().
>       - Use dev_err_probe instead of dev_err.
>       - Change dev_info to dev_dbg.
>       - Remove some empty lines.
>       - Fix MODULE_ALIAS to platform:pwm-visconti.
>       - Add .get_state() function.
>       - Use the author name and email address to MODULE_AUTHOR.
>       - Add more comment to function of the hardware.
>       - Support .get_status() function.
>       - Use NSEC_PER_USEC instead of 1000.
>       - Alphabetically sorted for Makefile and Kconfig.
>       - Added check for set value in visconti_pwm_apply().
> 
> Nobuhiro Iwamatsu (2):
>   dt-bindings: pwm: Add bindings for Toshiba Visconti PWM Controller
>   pwm: visconti: Add Toshiba Visconti SoC PWM support
> 
>  .../bindings/pwm/toshiba,pwm-visconti.yaml    |  43 ++++
>  drivers/pwm/Kconfig                           |   9 +
>  drivers/pwm/Makefile                          |   1 +
>  drivers/pwm/pwm-visconti.c                    | 189 ++++++++++++++++++
>  4 files changed, 242 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/pwm/toshiba,pwm-visconti.yaml
>  create mode 100644 drivers/pwm/pwm-visconti.c

Both patches applied, thanks.

checkpatch did complain when I applied:

> WARNING: please write a paragraph that describes the config symbol fully
> #9: FILE: drivers/pwm/Kconfig:604:
> +config PWM_VISCONTI

That seems a bit excessive. The paragraph is perhaps not a poster child
for Kconfig, but there are others that aren't better, so I think that's
fine.

> WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?
> #32: 
> new file mode 100644

Fine, too.

> WARNING: 'loosing' may be misspelled - perhaps 'losing'?
> #112: FILE: drivers/pwm/pwm-visconti.c:76:
>  +	 * NSEC_PER_SEC / CLKFREQ = 1000 without loosing precision.
>   	                                         ^^^^^^^

I've fixed that up while applying.

> WARNING: Avoid crashing the kernel - try using WARN_ON & recovery code rather than BUG() or BUG_ON()
> #127: FILE: drivers/pwm/pwm-visconti.c:91:
> +		BUG_ON(pwmc0 > 3);

I think that one is legit. I've turned that into:

	if (WARN_ON(pwmc0 > 3))
		return -EINVAL;

so that requests for too big period will be rejected rather than crash
the system. Next time, please run checkpatch before submitting and
eliminate at least the big warnings.

Thierry

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Re: [PATCH v6 0/2] pwm: visconti: Add Toshiba Visconti SoC PWM support

[Thierry Reding]

[-- Attachment #1.1: Type: text/plain, Size: 4657 bytes --]

On Mon, Apr 19, 2021 at 09:00:05AM +0900, Nobuhiro Iwamatsu wrote:
> Hi,
> 
> This series is the PWM driver for Toshiba's ARM SoC, Visconti[0].
> This provides DT binding documentation and device driver.
> 
> [0]: https://toshiba.semicon-storage.com/ap-en/semiconductor/product/image-recognition-processors-visconti.html
> 
> Updates:
> 
>   dt-bindings: pwm: Add bindings for Toshiba Visconti PWM Controller
>     v5 -> v6:
>       - No update.
>     v4 -> v5:
>       - No update.
>     v3 -> v4:
>       - No update.
>     v2 -> v3:
>       - Change compatible to toshiba,visconti-pwm
>       - Change filename to toshiba,visconti-pwm.yaml.
>       - Add Reviewed-by tag from Rob.
>     v1 -> v2:
>       - Change SPDX-License-Identifier to GPL-2.0-only OR BSD-2-Clause.
>       - Set compatible toshiba,pwm-visconti only.
>       - Drop unnecessary comments.
> 
>   pwm: visconti: Add Toshiba Visconti SoC PWM support
>     v5 -> v6:
>      - Update year in copyright.
>      - Update limitations.
>      - Fix coding style, used braces for both branches.
>     v4 -> v5:
>       - Droped checking PIPGM_PCSR from visconti_pwm_get_state.
>       - Changed from to_visconti_chip to visconti_pwm_from_chip.
>       - Removed pwmchip_remove return value management.
>       - Add limitations of this device.
>       - Add 'state->enabled = true' to visconti_pwm_get_state().
>     v3 -> v4:
>       - Sorted alphabetically include files.
>       - Changed container_of to using static inline functions.
>       - Dropped unnecessary dev_dbg().
>       - Drop Initialization of chip.base.
>       - Drop commnet "period too small".
>       - Rebased for-next. 
>     v2 -> v3:
>       - Change compatible to toshiba,visconti-pwm.
>       - Fix MODULE_ALIAS to platform:pwm-visconti, again.
>       - Align continuation line to the opening parenthesis.
>       - Rewrite the contents of visconti_pwm_apply() based on the contents suggested by Uwe.
>     v1 -> v2:
>       - Change SPDX-License-Identifier to GPL-2.0-only.
>       - Add prefix for the register defines.
>       - Drop struct device from struct visconti_pwm_chip.
>       - Use '>>' instead of '/'.
>       - Drop error message by devm_platform_ioremap_resource().
>       - Use dev_err_probe instead of dev_err.
>       - Change dev_info to dev_dbg.
>       - Remove some empty lines.
>       - Fix MODULE_ALIAS to platform:pwm-visconti.
>       - Add .get_state() function.
>       - Use the author name and email address to MODULE_AUTHOR.
>       - Add more comment to function of the hardware.
>       - Support .get_status() function.
>       - Use NSEC_PER_USEC instead of 1000.
>       - Alphabetically sorted for Makefile and Kconfig.
>       - Added check for set value in visconti_pwm_apply().
> 
> Nobuhiro Iwamatsu (2):
>   dt-bindings: pwm: Add bindings for Toshiba Visconti PWM Controller
>   pwm: visconti: Add Toshiba Visconti SoC PWM support
> 
>  .../bindings/pwm/toshiba,pwm-visconti.yaml    |  43 ++++
>  drivers/pwm/Kconfig                           |   9 +
>  drivers/pwm/Makefile                          |   1 +
>  drivers/pwm/pwm-visconti.c                    | 189 ++++++++++++++++++
>  4 files changed, 242 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/pwm/toshiba,pwm-visconti.yaml
>  create mode 100644 drivers/pwm/pwm-visconti.c

Both patches applied, thanks.

checkpatch did complain when I applied:

> WARNING: please write a paragraph that describes the config symbol fully
> #9: FILE: drivers/pwm/Kconfig:604:
> +config PWM_VISCONTI

That seems a bit excessive. The paragraph is perhaps not a poster child
for Kconfig, but there are others that aren't better, so I think that's
fine.

> WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?
> #32: 
> new file mode 100644

Fine, too.

> WARNING: 'loosing' may be misspelled - perhaps 'losing'?
> #112: FILE: drivers/pwm/pwm-visconti.c:76:
>  +	 * NSEC_PER_SEC / CLKFREQ = 1000 without loosing precision.
>   	                                         ^^^^^^^

I've fixed that up while applying.

> WARNING: Avoid crashing the kernel - try using WARN_ON & recovery code rather than BUG() or BUG_ON()
> #127: FILE: drivers/pwm/pwm-visconti.c:91:
> +		BUG_ON(pwmc0 > 3);

I think that one is legit. I've turned that into:

	if (WARN_ON(pwmc0 > 3))
		return -EINVAL;

so that requests for too big period will be rejected rather than crash
the system. Next time, please run checkpatch before submitting and
eliminate at least the big warnings.

Thierry

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Re: [PATCH v6 0/2] pwm: visconti: Add Toshiba Visconti SoC PWM support

[Uwe Kleine-König]

[-- Attachment #1: Type: text/plain, Size: 5625 bytes --]

On Fri, Apr 23, 2021 at 07:05:35PM +0200, Thierry Reding wrote:
> On Mon, Apr 19, 2021 at 09:00:05AM +0900, Nobuhiro Iwamatsu wrote:
> > Hi,
> > 
> > This series is the PWM driver for Toshiba's ARM SoC, Visconti[0].
> > This provides DT binding documentation and device driver.
> > 
> > [0]: https://toshiba.semicon-storage.com/ap-en/semiconductor/product/image-recognition-processors-visconti.html
> > 
> > Updates:
> > 
> >   dt-bindings: pwm: Add bindings for Toshiba Visconti PWM Controller
> >     v5 -> v6:
> >       - No update.
> >     v4 -> v5:
> >       - No update.
> >     v3 -> v4:
> >       - No update.
> >     v2 -> v3:
> >       - Change compatible to toshiba,visconti-pwm
> >       - Change filename to toshiba,visconti-pwm.yaml.
> >       - Add Reviewed-by tag from Rob.
> >     v1 -> v2:
> >       - Change SPDX-License-Identifier to GPL-2.0-only OR BSD-2-Clause.
> >       - Set compatible toshiba,pwm-visconti only.
> >       - Drop unnecessary comments.
> > 
> >   pwm: visconti: Add Toshiba Visconti SoC PWM support
> >     v5 -> v6:
> >      - Update year in copyright.
> >      - Update limitations.
> >      - Fix coding style, used braces for both branches.
> >     v4 -> v5:
> >       - Droped checking PIPGM_PCSR from visconti_pwm_get_state.
> >       - Changed from to_visconti_chip to visconti_pwm_from_chip.
> >       - Removed pwmchip_remove return value management.
> >       - Add limitations of this device.
> >       - Add 'state->enabled = true' to visconti_pwm_get_state().
> >     v3 -> v4:
> >       - Sorted alphabetically include files.
> >       - Changed container_of to using static inline functions.
> >       - Dropped unnecessary dev_dbg().
> >       - Drop Initialization of chip.base.
> >       - Drop commnet "period too small".
> >       - Rebased for-next. 
> >     v2 -> v3:
> >       - Change compatible to toshiba,visconti-pwm.
> >       - Fix MODULE_ALIAS to platform:pwm-visconti, again.
> >       - Align continuation line to the opening parenthesis.
> >       - Rewrite the contents of visconti_pwm_apply() based on the contents suggested by Uwe.
> >     v1 -> v2:
> >       - Change SPDX-License-Identifier to GPL-2.0-only.
> >       - Add prefix for the register defines.
> >       - Drop struct device from struct visconti_pwm_chip.
> >       - Use '>>' instead of '/'.
> >       - Drop error message by devm_platform_ioremap_resource().
> >       - Use dev_err_probe instead of dev_err.
> >       - Change dev_info to dev_dbg.
> >       - Remove some empty lines.
> >       - Fix MODULE_ALIAS to platform:pwm-visconti.
> >       - Add .get_state() function.
> >       - Use the author name and email address to MODULE_AUTHOR.
> >       - Add more comment to function of the hardware.
> >       - Support .get_status() function.
> >       - Use NSEC_PER_USEC instead of 1000.
> >       - Alphabetically sorted for Makefile and Kconfig.
> >       - Added check for set value in visconti_pwm_apply().
> > 
> > Nobuhiro Iwamatsu (2):
> >   dt-bindings: pwm: Add bindings for Toshiba Visconti PWM Controller
> >   pwm: visconti: Add Toshiba Visconti SoC PWM support
> > 
> >  .../bindings/pwm/toshiba,pwm-visconti.yaml    |  43 ++++
> >  drivers/pwm/Kconfig                           |   9 +
> >  drivers/pwm/Makefile                          |   1 +
> >  drivers/pwm/pwm-visconti.c                    | 189 ++++++++++++++++++
> >  4 files changed, 242 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/pwm/toshiba,pwm-visconti.yaml
> >  create mode 100644 drivers/pwm/pwm-visconti.c
> 
> Both patches applied, thanks.
> 
> checkpatch did complain when I applied:
> 
> > WARNING: please write a paragraph that describes the config symbol fully
> > #9: FILE: drivers/pwm/Kconfig:604:
> > +config PWM_VISCONTI
> 
> That seems a bit excessive. The paragraph is perhaps not a poster child
> for Kconfig, but there are others that aren't better, so I think that's
> fine.
> 
> > WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?
> > #32: 
> > new file mode 100644
> 
> Fine, too.
> 
> > WARNING: 'loosing' may be misspelled - perhaps 'losing'?
> > #112: FILE: drivers/pwm/pwm-visconti.c:76:
> >  +	 * NSEC_PER_SEC / CLKFREQ = 1000 without loosing precision.
> >   	                                         ^^^^^^^
> 
> I've fixed that up while applying.
> 
> > WARNING: Avoid crashing the kernel - try using WARN_ON & recovery code rather than BUG() or BUG_ON()
> > #127: FILE: drivers/pwm/pwm-visconti.c:91:
> > +		BUG_ON(pwmc0 > 3);
> 
> I think that one is legit. I've turned that into:
> 
> 	if (WARN_ON(pwmc0 > 3))
> 		return -EINVAL;

> 
> so that requests for too big period will be rejected rather than crash
> the system.

If this BUG_ON (or your if) triggers we have a compiler or memory
problem. The relevant parts of the code are:

	if (state->period > (0xffff << 3) * 1000)
		period = (0xffff << 3) * 1000;
	else
		period = state->period;

	period /= 1000;

	if (period > 0xffff) {
		pwmc0 = ilog2(period >> 16);
		BUG_ON(pwmc0 > 3);

Given that period is never bigger than 0xffff << 3 when it is used to
calculate the argument to ilog2, pwmc0 <= ilog2(7) = 2.

Hmm, I wonder if the formula is wrong given that pwmc0 never becomes 3?!
Should this better be

	pwmc0 = fls(period >> 16);

?

Best regards
Uwe

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

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Re: [PATCH v6 0/2] pwm: visconti: Add Toshiba Visconti SoC PWM support

[Uwe Kleine-König]

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On Fri, Apr 23, 2021 at 07:05:35PM +0200, Thierry Reding wrote:
> On Mon, Apr 19, 2021 at 09:00:05AM +0900, Nobuhiro Iwamatsu wrote:
> > Hi,
> > 
> > This series is the PWM driver for Toshiba's ARM SoC, Visconti[0].
> > This provides DT binding documentation and device driver.
> > 
> > [0]: https://toshiba.semicon-storage.com/ap-en/semiconductor/product/image-recognition-processors-visconti.html
> > 
> > Updates:
> > 
> >   dt-bindings: pwm: Add bindings for Toshiba Visconti PWM Controller
> >     v5 -> v6:
> >       - No update.
> >     v4 -> v5:
> >       - No update.
> >     v3 -> v4:
> >       - No update.
> >     v2 -> v3:
> >       - Change compatible to toshiba,visconti-pwm
> >       - Change filename to toshiba,visconti-pwm.yaml.
> >       - Add Reviewed-by tag from Rob.
> >     v1 -> v2:
> >       - Change SPDX-License-Identifier to GPL-2.0-only OR BSD-2-Clause.
> >       - Set compatible toshiba,pwm-visconti only.
> >       - Drop unnecessary comments.
> > 
> >   pwm: visconti: Add Toshiba Visconti SoC PWM support
> >     v5 -> v6:
> >      - Update year in copyright.
> >      - Update limitations.
> >      - Fix coding style, used braces for both branches.
> >     v4 -> v5:
> >       - Droped checking PIPGM_PCSR from visconti_pwm_get_state.
> >       - Changed from to_visconti_chip to visconti_pwm_from_chip.
> >       - Removed pwmchip_remove return value management.
> >       - Add limitations of this device.
> >       - Add 'state->enabled = true' to visconti_pwm_get_state().
> >     v3 -> v4:
> >       - Sorted alphabetically include files.
> >       - Changed container_of to using static inline functions.
> >       - Dropped unnecessary dev_dbg().
> >       - Drop Initialization of chip.base.
> >       - Drop commnet "period too small".
> >       - Rebased for-next. 
> >     v2 -> v3:
> >       - Change compatible to toshiba,visconti-pwm.
> >       - Fix MODULE_ALIAS to platform:pwm-visconti, again.
> >       - Align continuation line to the opening parenthesis.
> >       - Rewrite the contents of visconti_pwm_apply() based on the contents suggested by Uwe.
> >     v1 -> v2:
> >       - Change SPDX-License-Identifier to GPL-2.0-only.
> >       - Add prefix for the register defines.
> >       - Drop struct device from struct visconti_pwm_chip.
> >       - Use '>>' instead of '/'.
> >       - Drop error message by devm_platform_ioremap_resource().
> >       - Use dev_err_probe instead of dev_err.
> >       - Change dev_info to dev_dbg.
> >       - Remove some empty lines.
> >       - Fix MODULE_ALIAS to platform:pwm-visconti.
> >       - Add .get_state() function.
> >       - Use the author name and email address to MODULE_AUTHOR.
> >       - Add more comment to function of the hardware.
> >       - Support .get_status() function.
> >       - Use NSEC_PER_USEC instead of 1000.
> >       - Alphabetically sorted for Makefile and Kconfig.
> >       - Added check for set value in visconti_pwm_apply().
> > 
> > Nobuhiro Iwamatsu (2):
> >   dt-bindings: pwm: Add bindings for Toshiba Visconti PWM Controller
> >   pwm: visconti: Add Toshiba Visconti SoC PWM support
> > 
> >  .../bindings/pwm/toshiba,pwm-visconti.yaml    |  43 ++++
> >  drivers/pwm/Kconfig                           |   9 +
> >  drivers/pwm/Makefile                          |   1 +
> >  drivers/pwm/pwm-visconti.c                    | 189 ++++++++++++++++++
> >  4 files changed, 242 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/pwm/toshiba,pwm-visconti.yaml
> >  create mode 100644 drivers/pwm/pwm-visconti.c
> 
> Both patches applied, thanks.
> 
> checkpatch did complain when I applied:
> 
> > WARNING: please write a paragraph that describes the config symbol fully
> > #9: FILE: drivers/pwm/Kconfig:604:
> > +config PWM_VISCONTI
> 
> That seems a bit excessive. The paragraph is perhaps not a poster child
> for Kconfig, but there are others that aren't better, so I think that's
> fine.
> 
> > WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?
> > #32: 
> > new file mode 100644
> 
> Fine, too.
> 
> > WARNING: 'loosing' may be misspelled - perhaps 'losing'?
> > #112: FILE: drivers/pwm/pwm-visconti.c:76:
> >  +	 * NSEC_PER_SEC / CLKFREQ = 1000 without loosing precision.
> >   	                                         ^^^^^^^
> 
> I've fixed that up while applying.
> 
> > WARNING: Avoid crashing the kernel - try using WARN_ON & recovery code rather than BUG() or BUG_ON()
> > #127: FILE: drivers/pwm/pwm-visconti.c:91:
> > +		BUG_ON(pwmc0 > 3);
> 
> I think that one is legit. I've turned that into:
> 
> 	if (WARN_ON(pwmc0 > 3))
> 		return -EINVAL;

> 
> so that requests for too big period will be rejected rather than crash
> the system.

If this BUG_ON (or your if) triggers we have a compiler or memory
problem. The relevant parts of the code are:

	if (state->period > (0xffff << 3) * 1000)
		period = (0xffff << 3) * 1000;
	else
		period = state->period;

	period /= 1000;

	if (period > 0xffff) {
		pwmc0 = ilog2(period >> 16);
		BUG_ON(pwmc0 > 3);

Given that period is never bigger than 0xffff << 3 when it is used to
calculate the argument to ilog2, pwmc0 <= ilog2(7) = 2.

Hmm, I wonder if the formula is wrong given that pwmc0 never becomes 3?!
Should this better be

	pwmc0 = fls(period >> 16);

?

Best regards
Uwe

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

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