Re: [PATCH V4] PWM: Add SPEAr PWM chip driver support
On Wed, Oct 24, 2012 at 07:51:37AM +0200, Thierry Reding wrote:
> On Mon, Oct 22, 2012 at 04:36:41PM +0530, Shiraz Hashim wrote:
> [...]
> > +struct spear_pwm_chip {
> > + void __iomem *mmio_base;
> > + struct clk *clk;
> > + struct pwm_chip chip;
>
> My editor shows a tab between pwm_chip and chip. This should really be a
> space.
>
> > + ret = pwmchip_add(>chip);
> > + if (ret < 0) {
> > + dev_err(>dev, "pwmchip_add() failed: %d\n", ret);
> > + return ret;
> > + }
> > +
> > + ret = clk_prepare_enable(pc->clk);
> > + if (ret < 0)
> > + return pwmchip_remove(>chip);
>
> I think in order to fix the potential race condition that Viresh
> mentioned we should move the clk_prepare_enable() before the
> pwmchip_add(), but don't forget to disable and unprepare the clock if
> pwmchip_add() fails.
>
> Actually, can't we make it a clk_prepare() only at this point and move
> the clk_enable() and clk_disable() into the if block below? In case the
> compatible value is not "st,spear1340-pwm" we don't need the clock
> enabled.
>
> > +
> > + if (of_device_is_compatible(np, "st,spear1340-pwm")) {
> > + /*
> > +* Following enables PWM chip, channels would still be
> > +* enabled individually through their control register
> > +*/
> > + val = readl_relaxed(pc->mmio_base + PWMMCR);
> > + val |= PWMMCR_PWM_ENABLE;
> > + writel_relaxed(val, pc->mmio_base + PWMMCR);
> > +
>
> Oh, and a spurious newline here... =)
>
> > + }
> > +
> > + /* only disable the clk and leave it prepared */
> > + clk_disable(pc->clk);
>
> This can go into the if block to match the clk_enable().
All suggestions would be included in V5. I hope this would be the
last one :).
--
regards
Shiraz
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Re: [PATCH V4] PWM: Add SPEAr PWM chip driver support
On 24 October 2012 11:21, Thierry Reding
wrote:
> On Mon, Oct 22, 2012 at 04:36:41PM +0530, Shiraz Hashim wrote:
>> + ret = pwmchip_add(>chip);
>> + if (ret < 0) {
>> + dev_err(>dev, "pwmchip_add() failed: %d\n", ret);
>> + return ret;
>> + }
>> +
>> + ret = clk_prepare_enable(pc->clk);
>> + if (ret < 0)
>> + return pwmchip_remove(>chip);
>
> I think in order to fix the potential race condition that Viresh
> mentioned we should move the clk_prepare_enable() before the
> pwmchip_add(), but don't forget to disable and unprepare the clock if
> pwmchip_add() fails.
>
> Actually, can't we make it a clk_prepare() only at this point and move
> the clk_enable() and clk_disable() into the if block below? In case the
> compatible value is not "st,spear1340-pwm" we don't need the clock
> enabled.
We should. I should have given this comment earlier.
--
viresh
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Re: [PATCH V4] PWM: Add SPEAr PWM chip driver support
On 24 October 2012 11:21, Thierry Reding
thierry.red...@avionic-design.de wrote:
On Mon, Oct 22, 2012 at 04:36:41PM +0530, Shiraz Hashim wrote:
+ ret = pwmchip_add(pc-chip);
+ if (ret 0) {
+ dev_err(pdev-dev, pwmchip_add() failed: %d\n, ret);
+ return ret;
+ }
+
+ ret = clk_prepare_enable(pc-clk);
+ if (ret 0)
+ return pwmchip_remove(pc-chip);
I think in order to fix the potential race condition that Viresh
mentioned we should move the clk_prepare_enable() before the
pwmchip_add(), but don't forget to disable and unprepare the clock if
pwmchip_add() fails.
Actually, can't we make it a clk_prepare() only at this point and move
the clk_enable() and clk_disable() into the if block below? In case the
compatible value is not st,spear1340-pwm we don't need the clock
enabled.
We should. I should have given this comment earlier.
--
viresh
--
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Re: [PATCH V4] PWM: Add SPEAr PWM chip driver support
On Wed, Oct 24, 2012 at 07:51:37AM +0200, Thierry Reding wrote:
On Mon, Oct 22, 2012 at 04:36:41PM +0530, Shiraz Hashim wrote:
[...]
+struct spear_pwm_chip {
+ void __iomem *mmio_base;
+ struct clk *clk;
+ struct pwm_chip chip;
My editor shows a tab between pwm_chip and chip. This should really be a
space.
+ ret = pwmchip_add(pc-chip);
+ if (ret 0) {
+ dev_err(pdev-dev, pwmchip_add() failed: %d\n, ret);
+ return ret;
+ }
+
+ ret = clk_prepare_enable(pc-clk);
+ if (ret 0)
+ return pwmchip_remove(pc-chip);
I think in order to fix the potential race condition that Viresh
mentioned we should move the clk_prepare_enable() before the
pwmchip_add(), but don't forget to disable and unprepare the clock if
pwmchip_add() fails.
Actually, can't we make it a clk_prepare() only at this point and move
the clk_enable() and clk_disable() into the if block below? In case the
compatible value is not st,spear1340-pwm we don't need the clock
enabled.
+
+ if (of_device_is_compatible(np, st,spear1340-pwm)) {
+ /*
+* Following enables PWM chip, channels would still be
+* enabled individually through their control register
+*/
+ val = readl_relaxed(pc-mmio_base + PWMMCR);
+ val |= PWMMCR_PWM_ENABLE;
+ writel_relaxed(val, pc-mmio_base + PWMMCR);
+
Oh, and a spurious newline here... =)
+ }
+
+ /* only disable the clk and leave it prepared */
+ clk_disable(pc-clk);
This can go into the if block to match the clk_enable().
All suggestions would be included in V5. I hope this would be the
last one :).
--
regards
Shiraz
--
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the body of a message to majord...@vger.kernel.org
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Re: [PATCH V4] PWM: Add SPEAr PWM chip driver support
On Mon, Oct 22, 2012 at 04:36:41PM +0530, Shiraz Hashim wrote:
[...]
> +struct spear_pwm_chip {
> + void __iomem *mmio_base;
> + struct clk *clk;
> + struct pwm_chip chip;
My editor shows a tab between pwm_chip and chip. This should really be a
space.
> + ret = pwmchip_add(>chip);
> + if (ret < 0) {
> + dev_err(>dev, "pwmchip_add() failed: %d\n", ret);
> + return ret;
> + }
> +
> + ret = clk_prepare_enable(pc->clk);
> + if (ret < 0)
> + return pwmchip_remove(>chip);
I think in order to fix the potential race condition that Viresh
mentioned we should move the clk_prepare_enable() before the
pwmchip_add(), but don't forget to disable and unprepare the clock if
pwmchip_add() fails.
Actually, can't we make it a clk_prepare() only at this point and move
the clk_enable() and clk_disable() into the if block below? In case the
compatible value is not "st,spear1340-pwm" we don't need the clock
enabled.
> +
> + if (of_device_is_compatible(np, "st,spear1340-pwm")) {
> + /*
> + * Following enables PWM chip, channels would still be
> + * enabled individually through their control register
> + */
> + val = readl_relaxed(pc->mmio_base + PWMMCR);
> + val |= PWMMCR_PWM_ENABLE;
> + writel_relaxed(val, pc->mmio_base + PWMMCR);
> +
Oh, and a spurious newline here... =)
> + }
> +
> + /* only disable the clk and leave it prepared */
> + clk_disable(pc->clk);
This can go into the if block to match the clk_enable().
Thierry
pgpaMIyao45I9.pgp
Description: PGP signature
Re: [PATCH V4] PWM: Add SPEAr PWM chip driver support
On Mon, Oct 22, 2012 at 07:25:45PM +0530, Viresh Kumar wrote:
> On 22 October 2012 16:36, Shiraz Hashim wrote:
> > Add support for PWM chips present on SPEAr platforms. These PWM
> > chips support 4 channel output with programmable duty cycle and
> > frequency.
> >
> > More details on these PWM chips can be obtained from relevant
> > chapter of reference manual, present at following[1] location.
> >
> > 1. http://www.st.com/internet/mcu/product/251211.jsp
> >
> > Cc: Thierry Reding
> > Signed-off-by: Shiraz Hashim
> > Signed-off-by: Viresh Kumar
> > Reviewed-by: Vipin Kumar
>
> Acked-by: Viresh Kumar
>
> > diff --git a/drivers/pwm/pwm-spear.c b/drivers/pwm/pwm-spear.c
> > +static int spear_pwm_probe(struct platform_device *pdev)
> > +{
>
> > + ret = pwmchip_add(>chip);
> > + if (ret < 0) {
> > + dev_err(>dev, "pwmchip_add() failed: %d\n", ret);
> > + return ret;
> > + }
>
> Sorry couldn't think of this complex situation earlier :(
>
> Can it happen that we get a request for a pwm here and its config or enable
> gets called...?
>
> If yes, then we must call clk_prepare() before doing pwmchip_add?? Otherwise
> you will see a crash :)
>
> @Thierry: Can this happen?
Yeah, it's very unlikely to happen, but it could. See my reply to the
patch.
Thierry
pgprkqPNAr0tc.pgp
Description: PGP signature
Re: [PATCH V4] PWM: Add SPEAr PWM chip driver support
On Mon, Oct 22, 2012 at 07:25:45PM +0530, Viresh Kumar wrote:
On 22 October 2012 16:36, Shiraz Hashim shiraz.has...@st.com wrote:
Add support for PWM chips present on SPEAr platforms. These PWM
chips support 4 channel output with programmable duty cycle and
frequency.
More details on these PWM chips can be obtained from relevant
chapter of reference manual, present at following[1] location.
1. http://www.st.com/internet/mcu/product/251211.jsp
Cc: Thierry Reding thierry.red...@avionic-design.de
Signed-off-by: Shiraz Hashim shiraz.has...@st.com
Signed-off-by: Viresh Kumar viresh.ku...@linaro.org
Reviewed-by: Vipin Kumar vipin.ku...@st.com
Acked-by: Viresh Kumar viresh.ku...@linaro.org
diff --git a/drivers/pwm/pwm-spear.c b/drivers/pwm/pwm-spear.c
+static int spear_pwm_probe(struct platform_device *pdev)
+{
+ ret = pwmchip_add(pc-chip);
+ if (ret 0) {
+ dev_err(pdev-dev, pwmchip_add() failed: %d\n, ret);
+ return ret;
+ }
Sorry couldn't think of this complex situation earlier :(
Can it happen that we get a request for a pwm here and its config or enable
gets called...?
If yes, then we must call clk_prepare() before doing pwmchip_add?? Otherwise
you will see a crash :)
@Thierry: Can this happen?
Yeah, it's very unlikely to happen, but it could. See my reply to the
patch.
Thierry
pgprkqPNAr0tc.pgp
Description: PGP signature
Re: [PATCH V4] PWM: Add SPEAr PWM chip driver support
On Mon, Oct 22, 2012 at 04:36:41PM +0530, Shiraz Hashim wrote:
[...]
+struct spear_pwm_chip {
+ void __iomem *mmio_base;
+ struct clk *clk;
+ struct pwm_chip chip;
My editor shows a tab between pwm_chip and chip. This should really be a
space.
+ ret = pwmchip_add(pc-chip);
+ if (ret 0) {
+ dev_err(pdev-dev, pwmchip_add() failed: %d\n, ret);
+ return ret;
+ }
+
+ ret = clk_prepare_enable(pc-clk);
+ if (ret 0)
+ return pwmchip_remove(pc-chip);
I think in order to fix the potential race condition that Viresh
mentioned we should move the clk_prepare_enable() before the
pwmchip_add(), but don't forget to disable and unprepare the clock if
pwmchip_add() fails.
Actually, can't we make it a clk_prepare() only at this point and move
the clk_enable() and clk_disable() into the if block below? In case the
compatible value is not st,spear1340-pwm we don't need the clock
enabled.
+
+ if (of_device_is_compatible(np, st,spear1340-pwm)) {
+ /*
+ * Following enables PWM chip, channels would still be
+ * enabled individually through their control register
+ */
+ val = readl_relaxed(pc-mmio_base + PWMMCR);
+ val |= PWMMCR_PWM_ENABLE;
+ writel_relaxed(val, pc-mmio_base + PWMMCR);
+
Oh, and a spurious newline here... =)
+ }
+
+ /* only disable the clk and leave it prepared */
+ clk_disable(pc-clk);
This can go into the if block to match the clk_enable().
Thierry
pgpaMIyao45I9.pgp
Description: PGP signature
Re: [PATCH V4] PWM: Add SPEAr PWM chip driver support
On 22 October 2012 16:36, Shiraz Hashim wrote:
> Add support for PWM chips present on SPEAr platforms. These PWM
> chips support 4 channel output with programmable duty cycle and
> frequency.
>
> More details on these PWM chips can be obtained from relevant
> chapter of reference manual, present at following[1] location.
>
> 1. http://www.st.com/internet/mcu/product/251211.jsp
>
> Cc: Thierry Reding
> Signed-off-by: Shiraz Hashim
> Signed-off-by: Viresh Kumar
> Reviewed-by: Vipin Kumar
Acked-by: Viresh Kumar
> diff --git a/drivers/pwm/pwm-spear.c b/drivers/pwm/pwm-spear.c
> +static int spear_pwm_probe(struct platform_device *pdev)
> +{
> + ret = pwmchip_add(>chip);
> + if (ret < 0) {
> + dev_err(>dev, "pwmchip_add() failed: %d\n", ret);
> + return ret;
> + }
Sorry couldn't think of this complex situation earlier :(
Can it happen that we get a request for a pwm here and its config or enable
gets called...?
If yes, then we must call clk_prepare() before doing pwmchip_add?? Otherwise
you will see a crash :)
@Thierry: Can this happen?
> + ret = clk_prepare_enable(pc->clk);
> + if (ret < 0)
> + return pwmchip_remove(>chip);
--
viresh
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Please read the FAQ at http://www.tux.org/lkml/
[PATCH V4] PWM: Add SPEAr PWM chip driver support
Add support for PWM chips present on SPEAr platforms. These PWM
chips support 4 channel output with programmable duty cycle and
frequency.
More details on these PWM chips can be obtained from relevant
chapter of reference manual, present at following[1] location.
1. http://www.st.com/internet/mcu/product/251211.jsp
Cc: Thierry Reding
Signed-off-by: Shiraz Hashim
Signed-off-by: Viresh Kumar
Reviewed-by: Vipin Kumar
---
Changes:-
V3 --> V4:
* simplify remove
* maintain alphabetical order in Makefile
* donot check for device node in probe
* move few assignment lines in probe
V2 --> V3:
* remove "disabled" line from pwm dt binding documentation
* remove un-necessary check on pwm chip (for NULL) in remove.
V1 --> V2:
* make proper reference to pwm and pwm chip
* take care to capitalize PWM at appropriate places
* fix compatible string to the SoC where pwm chip was introduced
* Rename the documentation file to the name of driver
* Fix cosmetic changes like names, function name alignment, paragraph
formating, comments placement and formating, etc.
* Group and associate the bit field definitions to their registers
* Fix kerneldoc for structure definition
* Use chip to name pwm device and pwm for the channel instance
* Remove init section qualifiers
* Remove ifdefs around device tree from code and add dependency on CONFIG_OF
* prepare/unprepare clock once in probe/remove and just enable/disable
at rest of the places.
* Use _relaxed for readl/writel.
* Fix pwm disable part in remove
.../devicetree/bindings/pwm/spear-pwm.txt | 18 ++
drivers/pwm/Kconfig| 11 +
drivers/pwm/Makefile |1 +
drivers/pwm/pwm-spear.c| 273
4 files changed, 303 insertions(+)
create mode 100644 Documentation/devicetree/bindings/pwm/spear-pwm.txt
create mode 100644 drivers/pwm/pwm-spear.c
diff --git a/Documentation/devicetree/bindings/pwm/spear-pwm.txt
b/Documentation/devicetree/bindings/pwm/spear-pwm.txt
new file mode 100644
index 000..3ac779d
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/spear-pwm.txt
@@ -0,0 +1,18 @@
+== ST SPEAr SoC PWM controller ==
+
+Required properties:
+- compatible: should be one of:
+ - "st,spear320-pwm"
+ - "st,spear1340-pwm"
+- reg: physical base address and length of the controller's registers
+- #pwm-cells: number of cells used to specify PWM which is fixed to 2 on
+ SPEAr. The first cell specifies the per-chip index of the PWM to use and
+ the second cell is the period in nanoseconds.
+
+Example:
+
+pwm: pwm@a800 {
+compatible ="st,spear320-pwm";
+reg = <0xa800 0x1000>;
+#pwm-cells = <2>;
+};
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index ed81720..6e556c7 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -112,6 +112,17 @@ config PWM_SAMSUNG
To compile this driver as a module, choose M here: the module
will be called pwm-samsung.
+config PWM_SPEAR
+ tristate "STMicroelectronics SPEAr PWM support"
+ depends on PLAT_SPEAR
+ depends on OF
+ help
+ Generic PWM framework driver for the PWM controller on ST
+ SPEAr SoCs.
+
+ To compile this driver as a module, choose M here: the module
+ will be called pwm-spear.
+
config PWM_TEGRA
tristate "NVIDIA Tegra PWM support"
depends on ARCH_TEGRA
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index acfe482..3b3f4c9a 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_PWM_MXS) += pwm-mxs.o
obj-$(CONFIG_PWM_PUV3) += pwm-puv3.o
obj-$(CONFIG_PWM_PXA) += pwm-pxa.o
obj-$(CONFIG_PWM_SAMSUNG) += pwm-samsung.o
+obj-$(CONFIG_PWM_SPEAR)+= pwm-spear.o
obj-$(CONFIG_PWM_TEGRA)+= pwm-tegra.o
obj-$(CONFIG_PWM_TIECAP) += pwm-tiecap.o
obj-$(CONFIG_PWM_TIEHRPWM) += pwm-tiehrpwm.o
diff --git a/drivers/pwm/pwm-spear.c b/drivers/pwm/pwm-spear.c
new file mode 100644
index 000..35124a01
--- /dev/null
+++ b/drivers/pwm/pwm-spear.c
@@ -0,0 +1,273 @@
+/*
+ * ST Microelectronics SPEAr Pulse Width Modulator driver
+ *
+ * Copyright (C) 2012 ST Microelectronics
+ * Shiraz Hashim
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+
+#define NUM_PWM4
+
+/* PWM registers and bits definitions */
+#define PWMCR 0x00/* Control Register */
+#define PWMCR_PWM_ENABLE 0x1
+#define PWMCR_PRESCALE_SHIFT 2
+#define PWMCR_MIN_PRESCALE 0x00
+#define
[PATCH V4] PWM: Add SPEAr PWM chip driver support
Add support for PWM chips present on SPEAr platforms. These PWM
chips support 4 channel output with programmable duty cycle and
frequency.
More details on these PWM chips can be obtained from relevant
chapter of reference manual, present at following[1] location.
1. http://www.st.com/internet/mcu/product/251211.jsp
Cc: Thierry Reding thierry.red...@avionic-design.de
Signed-off-by: Shiraz Hashim shiraz.has...@st.com
Signed-off-by: Viresh Kumar viresh.ku...@linaro.org
Reviewed-by: Vipin Kumar vipin.ku...@st.com
---
Changes:-
V3 -- V4:
* simplify remove
* maintain alphabetical order in Makefile
* donot check for device node in probe
* move few assignment lines in probe
V2 -- V3:
* remove disabled line from pwm dt binding documentation
* remove un-necessary check on pwm chip (for NULL) in remove.
V1 -- V2:
* make proper reference to pwm and pwm chip
* take care to capitalize PWM at appropriate places
* fix compatible string to the SoC where pwm chip was introduced
* Rename the documentation file to the name of driver
* Fix cosmetic changes like names, function name alignment, paragraph
formating, comments placement and formating, etc.
* Group and associate the bit field definitions to their registers
* Fix kerneldoc for structure definition
* Use chip to name pwm device and pwm for the channel instance
* Remove init section qualifiers
* Remove ifdefs around device tree from code and add dependency on CONFIG_OF
* prepare/unprepare clock once in probe/remove and just enable/disable
at rest of the places.
* Use _relaxed for readl/writel.
* Fix pwm disable part in remove
.../devicetree/bindings/pwm/spear-pwm.txt | 18 ++
drivers/pwm/Kconfig| 11 +
drivers/pwm/Makefile |1 +
drivers/pwm/pwm-spear.c| 273
4 files changed, 303 insertions(+)
create mode 100644 Documentation/devicetree/bindings/pwm/spear-pwm.txt
create mode 100644 drivers/pwm/pwm-spear.c
diff --git a/Documentation/devicetree/bindings/pwm/spear-pwm.txt
b/Documentation/devicetree/bindings/pwm/spear-pwm.txt
new file mode 100644
index 000..3ac779d
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/spear-pwm.txt
@@ -0,0 +1,18 @@
+== ST SPEAr SoC PWM controller ==
+
+Required properties:
+- compatible: should be one of:
+ - st,spear320-pwm
+ - st,spear1340-pwm
+- reg: physical base address and length of the controller's registers
+- #pwm-cells: number of cells used to specify PWM which is fixed to 2 on
+ SPEAr. The first cell specifies the per-chip index of the PWM to use and
+ the second cell is the period in nanoseconds.
+
+Example:
+
+pwm: pwm@a800 {
+compatible =st,spear320-pwm;
+reg = 0xa800 0x1000;
+#pwm-cells = 2;
+};
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index ed81720..6e556c7 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -112,6 +112,17 @@ config PWM_SAMSUNG
To compile this driver as a module, choose M here: the module
will be called pwm-samsung.
+config PWM_SPEAR
+ tristate STMicroelectronics SPEAr PWM support
+ depends on PLAT_SPEAR
+ depends on OF
+ help
+ Generic PWM framework driver for the PWM controller on ST
+ SPEAr SoCs.
+
+ To compile this driver as a module, choose M here: the module
+ will be called pwm-spear.
+
config PWM_TEGRA
tristate NVIDIA Tegra PWM support
depends on ARCH_TEGRA
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index acfe482..3b3f4c9a 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_PWM_MXS) += pwm-mxs.o
obj-$(CONFIG_PWM_PUV3) += pwm-puv3.o
obj-$(CONFIG_PWM_PXA) += pwm-pxa.o
obj-$(CONFIG_PWM_SAMSUNG) += pwm-samsung.o
+obj-$(CONFIG_PWM_SPEAR)+= pwm-spear.o
obj-$(CONFIG_PWM_TEGRA)+= pwm-tegra.o
obj-$(CONFIG_PWM_TIECAP) += pwm-tiecap.o
obj-$(CONFIG_PWM_TIEHRPWM) += pwm-tiehrpwm.o
diff --git a/drivers/pwm/pwm-spear.c b/drivers/pwm/pwm-spear.c
new file mode 100644
index 000..35124a01
--- /dev/null
+++ b/drivers/pwm/pwm-spear.c
@@ -0,0 +1,273 @@
+/*
+ * ST Microelectronics SPEAr Pulse Width Modulator driver
+ *
+ * Copyright (C) 2012 ST Microelectronics
+ * Shiraz Hashim shiraz.has...@st.com
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed as is without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include linux/clk.h
+#include linux/err.h
+#include linux/io.h
+#include linux/ioport.h
+#include linux/kernel.h
+#include linux/math64.h
+#include linux/module.h
+#include linux/of.h
+#include linux/platform_device.h
+#include linux/pwm.h
+#include linux/slab.h
+#include linux/types.h
+
+#define NUM_PWM
Re: [PATCH V4] PWM: Add SPEAr PWM chip driver support
On 22 October 2012 16:36, Shiraz Hashim shiraz.has...@st.com wrote:
Add support for PWM chips present on SPEAr platforms. These PWM
chips support 4 channel output with programmable duty cycle and
frequency.
More details on these PWM chips can be obtained from relevant
chapter of reference manual, present at following[1] location.
1. http://www.st.com/internet/mcu/product/251211.jsp
Cc: Thierry Reding thierry.red...@avionic-design.de
Signed-off-by: Shiraz Hashim shiraz.has...@st.com
Signed-off-by: Viresh Kumar viresh.ku...@linaro.org
Reviewed-by: Vipin Kumar vipin.ku...@st.com
Acked-by: Viresh Kumar viresh.ku...@linaro.org
diff --git a/drivers/pwm/pwm-spear.c b/drivers/pwm/pwm-spear.c
+static int spear_pwm_probe(struct platform_device *pdev)
+{
+ ret = pwmchip_add(pc-chip);
+ if (ret 0) {
+ dev_err(pdev-dev, pwmchip_add() failed: %d\n, ret);
+ return ret;
+ }
Sorry couldn't think of this complex situation earlier :(
Can it happen that we get a request for a pwm here and its config or enable
gets called...?
If yes, then we must call clk_prepare() before doing pwmchip_add?? Otherwise
you will see a crash :)
@Thierry: Can this happen?
+ ret = clk_prepare_enable(pc-clk);
+ if (ret 0)
+ return pwmchip_remove(pc-chip);
--
viresh
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