[PATCH v2 0/7] FlexTimer Module Quadrature decoder counter

[PATCH v2 0/7] FlexTimer Module Quadrature decoder counter

[Patrick Havelange]

This patch serie is to be applied on top of 
https://patchwork.kernel.org/project/linux-iio/list/?series=147
(a more recent version of the serie is available here : 
https://gitlab.com/vilhelmgray/iio/tree/generic_counter_v10 )

Main changes in v2: 
The code is a bit simpler, thanks to more use of devm_* functions.
The polling/32bit signed version has been dropped, as not needed and
no other driver is doing that.


Patrick Havelange (7):
  include/fsl: add common FlexTimer #defines in a separate header.
  drivers/pwm: pwm-fsl-ftm: use common header for FlexTimer #defines
  drivers/clocksource: timer-fsl-ftm: use common header for FlexTimer
    #defines
  dt-bindings: counter: ftm-quaddec
  counter: add FlexTimer Module Quadrature decoder counter driver
  counter: ftm-quaddec: Documentation: Add specific counter sysfs
    documentation
  LS1021A: dtsi: add ftm quad decoder entries

 .../ABI/testing/sysfs-bus-counter-ftm-quaddec |  16 +
 .../bindings/counter/ftm-quaddec.txt          |  18 +
 arch/arm/boot/dts/ls1021a.dtsi                |  28 ++
 drivers/clocksource/timer-fsl-ftm.c           |  15 +-
 drivers/counter/Kconfig                       |   9 +
 drivers/counter/Makefile                      |   1 +
 drivers/counter/ftm-quaddec.c                 | 356 ++++++++++++++++++
 drivers/pwm/pwm-fsl-ftm.c                     |  44 +--
 include/linux/fsl/ftm.h                       |  88 +++++
 9 files changed, 519 insertions(+), 56 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-counter-ftm-quaddec
 create mode 100644 Documentation/devicetree/bindings/counter/ftm-quaddec.txt
 create mode 100644 drivers/counter/ftm-quaddec.c
 create mode 100644 include/linux/fsl/ftm.h

-- 
2.19.1

[PATCH v2 1/7] include/fsl: add common FlexTimer #defines in a separate header.

[Patrick Havelange]

Several files are/will be using the same #defines to use the Flextimer
module. Regroup them in a common file.

Signed-off-by: Patrick Havelange <patrick.havelange@essensium.com>
Reviewed-by: Esben Haabendal <esben@haabendal.dk>
---
Changes v2
     - Commit message
---
 include/linux/fsl/ftm.h | 88 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 88 insertions(+)
 create mode 100644 include/linux/fsl/ftm.h

diff --git a/include/linux/fsl/ftm.h b/include/linux/fsl/ftm.h
new file mode 100644
index 000000000000..d59011acf66c
--- /dev/null
+++ b/include/linux/fsl/ftm.h
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef __FSL_FTM_H__
+#define __FSL_FTM_H__
+
+#define FTM_SC       0x0 /* Status And Control */
+#define FTM_CNT      0x4 /* Counter */
+#define FTM_MOD      0x8 /* Modulo */
+
+#define FTM_CNTIN    0x4C /* Counter Initial Value */
+#define FTM_STATUS   0x50 /* Capture And Compare Status */
+#define FTM_MODE     0x54 /* Features Mode Selection */
+#define FTM_SYNC     0x58 /* Synchronization */
+#define FTM_OUTINIT  0x5C /* Initial State For Channels Output */
+#define FTM_OUTMASK  0x60 /* Output Mask */
+#define FTM_COMBINE  0x64 /* Function For Linked Channels */
+#define FTM_DEADTIME 0x68 /* Deadtime Insertion Control */
+#define FTM_EXTTRIG  0x6C /* FTM External Trigger */
+#define FTM_POL      0x70 /* Channels Polarity */
+#define FTM_FMS      0x74 /* Fault Mode Status */
+#define FTM_FILTER   0x78 /* Input Capture Filter Control */
+#define FTM_FLTCTRL  0x7C /* Fault Control */
+#define FTM_QDCTRL   0x80 /* Quadrature Decoder Control And Status */
+#define FTM_CONF     0x84 /* Configuration */
+#define FTM_FLTPOL   0x88 /* FTM Fault Input Polarity */
+#define FTM_SYNCONF  0x8C /* Synchronization Configuration */
+#define FTM_INVCTRL  0x90 /* FTM Inverting Control */
+#define FTM_SWOCTRL  0x94 /* FTM Software Output Control */
+#define FTM_PWMLOAD  0x98 /* FTM PWM Load */
+
+#define FTM_SC_CLK_MASK_SHIFT	3
+#define FTM_SC_CLK_MASK		(3 << FTM_SC_CLK_MASK_SHIFT)
+#define FTM_SC_TOF		0x80
+#define FTM_SC_TOIE		0x40
+#define FTM_SC_CPWMS		0x20
+#define FTM_SC_CLKS		0x18
+#define FTM_SC_PS_1		0x0
+#define FTM_SC_PS_2		0x1
+#define FTM_SC_PS_4		0x2
+#define FTM_SC_PS_8		0x3
+#define FTM_SC_PS_16		0x4
+#define FTM_SC_PS_32		0x5
+#define FTM_SC_PS_64		0x6
+#define FTM_SC_PS_128		0x7
+#define FTM_SC_PS_MASK		0x7
+
+#define FTM_MODE_FAULTIE	0x80
+#define FTM_MODE_FAULTM		0x60
+#define FTM_MODE_CAPTEST	0x10
+#define FTM_MODE_PWMSYNC	0x8
+#define FTM_MODE_WPDIS		0x4
+#define FTM_MODE_INIT		0x2
+#define FTM_MODE_FTMEN		0x1
+
+/* NXP Errata: The PHAFLTREN and PHBFLTREN bits are tide to zero internally
+ * and these bits cannot be set. Flextimer cannot use Filter in
+ * Quadrature Decoder Mode.
+ * https://community.nxp.com/thread/467648#comment-1010319
+ */
+#define FTM_QDCTRL_PHAFLTREN	0x80
+#define FTM_QDCTRL_PHBFLTREN	0x40
+#define FTM_QDCTRL_PHAPOL	0x20
+#define FTM_QDCTRL_PHBPOL	0x10
+#define FTM_QDCTRL_QUADMODE	0x8
+#define FTM_QDCTRL_QUADDIR	0x4
+#define FTM_QDCTRL_TOFDIR	0x2
+#define FTM_QDCTRL_QUADEN	0x1
+
+#define FTM_FMS_FAULTF		0x80
+#define FTM_FMS_WPEN		0x40
+#define FTM_FMS_FAULTIN		0x10
+#define FTM_FMS_FAULTF3		0x8
+#define FTM_FMS_FAULTF2		0x4
+#define FTM_FMS_FAULTF1		0x2
+#define FTM_FMS_FAULTF0		0x1
+
+#define FTM_CSC_BASE		0xC
+#define FTM_CSC_MSB		0x20
+#define FTM_CSC_MSA		0x10
+#define FTM_CSC_ELSB		0x8
+#define FTM_CSC_ELSA		0x4
+#define FTM_CSC(_channel)	(FTM_CSC_BASE + ((_channel) * 8))
+
+#define FTM_CV_BASE		0x10
+#define FTM_CV(_channel)	(FTM_CV_BASE + ((_channel) * 8))
+
+#define FTM_PS_MAX		7
+
+#endif
-- 
2.19.1

[PATCH v2 2/7] drivers/pwm: pwm-fsl-ftm: use common header for FlexTimer #defines

[Patrick Havelange]

This also fixes the wrong value for the previously defined
FTM_MODE_INIT macro (it was not used).

Signed-off-by: Patrick Havelange <patrick.havelange@essensium.com>
Reviewed-by: Esben Haabendal <esben@haabendal.dk>
---
Changes v2
     - None
---
 drivers/pwm/pwm-fsl-ftm.c | 44 +--------------------------------------
 1 file changed, 1 insertion(+), 43 deletions(-)

diff --git a/drivers/pwm/pwm-fsl-ftm.c b/drivers/pwm/pwm-fsl-ftm.c
index 883378d055c6..f21ea1b97116 100644
--- a/drivers/pwm/pwm-fsl-ftm.c
+++ b/drivers/pwm/pwm-fsl-ftm.c
@@ -22,51 +22,9 @@
 #include <linux/pwm.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>
+#include <linux/fsl/ftm.h>
 
-#define FTM_SC		0x00
-#define FTM_SC_CLK_MASK_SHIFT	3
-#define FTM_SC_CLK_MASK	(3 << FTM_SC_CLK_MASK_SHIFT)
 #define FTM_SC_CLK(c)	(((c) + 1) << FTM_SC_CLK_MASK_SHIFT)
-#define FTM_SC_PS_MASK	0x7
-
-#define FTM_CNT		0x04
-#define FTM_MOD		0x08
-
-#define FTM_CSC_BASE	0x0C
-#define FTM_CSC_MSB	BIT(5)
-#define FTM_CSC_MSA	BIT(4)
-#define FTM_CSC_ELSB	BIT(3)
-#define FTM_CSC_ELSA	BIT(2)
-#define FTM_CSC(_channel)	(FTM_CSC_BASE + ((_channel) * 8))
-
-#define FTM_CV_BASE	0x10
-#define FTM_CV(_channel)	(FTM_CV_BASE + ((_channel) * 8))
-
-#define FTM_CNTIN	0x4C
-#define FTM_STATUS	0x50
-
-#define FTM_MODE	0x54
-#define FTM_MODE_FTMEN	BIT(0)
-#define FTM_MODE_INIT	BIT(2)
-#define FTM_MODE_PWMSYNC	BIT(3)
-
-#define FTM_SYNC	0x58
-#define FTM_OUTINIT	0x5C
-#define FTM_OUTMASK	0x60
-#define FTM_COMBINE	0x64
-#define FTM_DEADTIME	0x68
-#define FTM_EXTTRIG	0x6C
-#define FTM_POL		0x70
-#define FTM_FMS		0x74
-#define FTM_FILTER	0x78
-#define FTM_FLTCTRL	0x7C
-#define FTM_QDCTRL	0x80
-#define FTM_CONF	0x84
-#define FTM_FLTPOL	0x88
-#define FTM_SYNCONF	0x8C
-#define FTM_INVCTRL	0x90
-#define FTM_SWOCTRL	0x94
-#define FTM_PWMLOAD	0x98
 
 enum fsl_pwm_clk {
 	FSL_PWM_CLK_SYS,
-- 
2.19.1

[PATCH v2 3/7] drivers/clocksource: timer-fsl-ftm: use common header for FlexTimer #defines

[Patrick Havelange]

Common #defines have been moved to "linux/fsl/ftm.h". Thus making use of
this file.
Also FTM_SC_CLK_SHIFT has been renamed to FTM_SC_CLK_MASK_SHIFT.

Signed-off-by: Patrick Havelange <patrick.havelange@essensium.com>
Reviewed-by: Esben Haabendal <esben@haabendal.dk>
---
Changes v2
     - None
---
 drivers/clocksource/timer-fsl-ftm.c | 15 ++-------------
 1 file changed, 2 insertions(+), 13 deletions(-)

diff --git a/drivers/clocksource/timer-fsl-ftm.c b/drivers/clocksource/timer-fsl-ftm.c
index 846d18daf893..e1c34b2f53a5 100644
--- a/drivers/clocksource/timer-fsl-ftm.c
+++ b/drivers/clocksource/timer-fsl-ftm.c
@@ -19,20 +19,9 @@
 #include <linux/of_irq.h>
 #include <linux/sched_clock.h>
 #include <linux/slab.h>
+#include <linux/fsl/ftm.h>
 
-#define FTM_SC		0x00
-#define FTM_SC_CLK_SHIFT	3
-#define FTM_SC_CLK_MASK	(0x3 << FTM_SC_CLK_SHIFT)
-#define FTM_SC_CLK(c)	((c) << FTM_SC_CLK_SHIFT)
-#define FTM_SC_PS_MASK	0x7
-#define FTM_SC_TOIE	BIT(6)
-#define FTM_SC_TOF	BIT(7)
-
-#define FTM_CNT		0x04
-#define FTM_MOD		0x08
-#define FTM_CNTIN	0x4C
-
-#define FTM_PS_MAX	7
+#define FTM_SC_CLK(c)	((c) << FTM_SC_CLK_MASK_SHIFT)
 
 struct ftm_clock_device {
 	void __iomem *clksrc_base;
-- 
2.19.1

Re: [PATCH v2 3/7] drivers/clocksource: timer-fsl-ftm: use common header for FlexTimer #defines

[Daniel Lezcano]

On 06/03/2019 12:12, Patrick Havelange wrote:
> Common #defines have been moved to "linux/fsl/ftm.h". Thus making use of
> this file.
> Also FTM_SC_CLK_SHIFT has been renamed to FTM_SC_CLK_MASK_SHIFT.
> 
> Signed-off-by: Patrick Havelange <patrick.havelange@essensium.com>
> Reviewed-by: Esben Haabendal <esben@haabendal.dk>

Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>

> ---
> Changes v2
>      - None
> ---
>  drivers/clocksource/timer-fsl-ftm.c | 15 ++-------------
>  1 file changed, 2 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/clocksource/timer-fsl-ftm.c b/drivers/clocksource/timer-fsl-ftm.c
> index 846d18daf893..e1c34b2f53a5 100644
> --- a/drivers/clocksource/timer-fsl-ftm.c
> +++ b/drivers/clocksource/timer-fsl-ftm.c
> @@ -19,20 +19,9 @@
>  #include <linux/of_irq.h>
>  #include <linux/sched_clock.h>
>  #include <linux/slab.h>
> +#include <linux/fsl/ftm.h>
>  
> -#define FTM_SC		0x00
> -#define FTM_SC_CLK_SHIFT	3
> -#define FTM_SC_CLK_MASK	(0x3 << FTM_SC_CLK_SHIFT)
> -#define FTM_SC_CLK(c)	((c) << FTM_SC_CLK_SHIFT)
> -#define FTM_SC_PS_MASK	0x7
> -#define FTM_SC_TOIE	BIT(6)
> -#define FTM_SC_TOF	BIT(7)
> -
> -#define FTM_CNT		0x04
> -#define FTM_MOD		0x08
> -#define FTM_CNTIN	0x4C
> -
> -#define FTM_PS_MAX	7
> +#define FTM_SC_CLK(c)	((c) << FTM_SC_CLK_MASK_SHIFT)
>  
>  struct ftm_clock_device {
>  	void __iomem *clksrc_base;
> 


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[PATCH v2 4/7] dt-bindings: counter: ftm-quaddec

[Patrick Havelange]

FlexTimer quadrature decoder driver.

Signed-off-by: Patrick Havelange <patrick.havelange@essensium.com>
Reviewed-by: Esben Haabendal <esben@haabendal.dk>
---
Changes v2
     - None
---
 .../bindings/counter/ftm-quaddec.txt           | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/counter/ftm-quaddec.txt

diff --git a/Documentation/devicetree/bindings/counter/ftm-quaddec.txt b/Documentation/devicetree/bindings/counter/ftm-quaddec.txt
new file mode 100644
index 000000000000..4d18cd722074
--- /dev/null
+++ b/Documentation/devicetree/bindings/counter/ftm-quaddec.txt
@@ -0,0 +1,18 @@
+FlexTimer Quadrature decoder counter
+
+This driver exposes a simple counter for the quadrature decoder mode.
+
+Required properties:
+- compatible:		Must be "fsl,ftm-quaddec".
+- reg:			Must be set to the memory region of the flextimer.
+
+Optional property:
+- big-endian:		Access the device registers in big-endian mode.
+
+Example:
+		counter0: counter@29d0000 {
+			compatible = "fsl,ftm-quaddec";
+			reg = <0x0 0x29d0000 0x0 0x10000>;
+			big-endian;
+			status = "disabled";
+		};
-- 
2.19.1

Re: [PATCH v2 4/7] dt-bindings: counter: ftm-quaddec

[Rob Herring]

On Wed, Mar 06, 2019 at 12:12:05PM +0100, Patrick Havelange wrote:
> FlexTimer quadrature decoder driver.
> 
> Signed-off-by: Patrick Havelange <patrick.havelange@essensium.com>
> Reviewed-by: Esben Haabendal <esben@haabendal.dk>
> ---
> Changes v2
>      - None
> ---
>  .../bindings/counter/ftm-quaddec.txt           | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/counter/ftm-quaddec.txt
> 
> diff --git a/Documentation/devicetree/bindings/counter/ftm-quaddec.txt b/Documentation/devicetree/bindings/counter/ftm-quaddec.txt
> new file mode 100644
> index 000000000000..4d18cd722074
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/counter/ftm-quaddec.txt
> @@ -0,0 +1,18 @@
> +FlexTimer Quadrature decoder counter
> +
> +This driver exposes a simple counter for the quadrature decoder mode.

Seems like this is more a mode of a h/w block than describing a h/w 
block. Bindings should do the latter.

> +
> +Required properties:
> +- compatible:		Must be "fsl,ftm-quaddec".
> +- reg:			Must be set to the memory region of the flextimer.
> +
> +Optional property:
> +- big-endian:		Access the device registers in big-endian mode.
> +
> +Example:
> +		counter0: counter@29d0000 {
> +			compatible = "fsl,ftm-quaddec";
> +			reg = <0x0 0x29d0000 0x0 0x10000>;
> +			big-endian;
> +			status = "disabled";
> +		};
> -- 
> 2.19.1
> 

Re: [PATCH v2 4/7] dt-bindings: counter: ftm-quaddec

[Jonathan Cameron]

On Tue, 12 Mar 2019 14:09:52 -0500
Rob Herring <robh@kernel.org> wrote:

> On Wed, Mar 06, 2019 at 12:12:05PM +0100, Patrick Havelange wrote:
> > FlexTimer quadrature decoder driver.
> > 
> > Signed-off-by: Patrick Havelange <patrick.havelange@essensium.com>
> > Reviewed-by: Esben Haabendal <esben@haabendal.dk>
> > ---
> > Changes v2
> >      - None
> > ---
> >  .../bindings/counter/ftm-quaddec.txt           | 18 ++++++++++++++++++
> >  1 file changed, 18 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/counter/ftm-quaddec.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/counter/ftm-quaddec.txt b/Documentation/devicetree/bindings/counter/ftm-quaddec.txt
> > new file mode 100644
> > index 000000000000..4d18cd722074
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/counter/ftm-quaddec.txt
> > @@ -0,0 +1,18 @@
> > +FlexTimer Quadrature decoder counter
> > +
> > +This driver exposes a simple counter for the quadrature decoder mode.  
> 
> Seems like this is more a mode of a h/w block than describing a h/w 
> block. Bindings should do the latter.
The snag is that we need to dig ourselves out of the hole set by:
fsl,vf610-ftm-pwm etc.

Documentation/devicetree/bindings/pwm/pwm-fsl-ftm.txt
Documentation/devicetree/bindings/timer/fsl,ftm-timer.txt
(I'm assuming these are the same IP block).

Can probably be sorted out though.  One core driver binds against the
ftm and deals with instantiating the others depending on the configuration
(note that this mode for instance does make sense in DT as it's
really reflecting the fact there is a quadrature encoder
connected to the ftm).

Fiddly though :)

J
> 
> > +
> > +Required properties:
> > +- compatible:		Must be "fsl,ftm-quaddec".
> > +- reg:			Must be set to the memory region of the flextimer.
> > +
> > +Optional property:
> > +- big-endian:		Access the device registers in big-endian mode.
> > +
> > +Example:
> > +		counter0: counter@29d0000 {
> > +			compatible = "fsl,ftm-quaddec";
> > +			reg = <0x0 0x29d0000 0x0 0x10000>;
> > +			big-endian;
> > +			status = "disabled";
> > +		};
> > -- 
> > 2.19.1
> >   

Re: [PATCH v2 4/7] dt-bindings: counter: ftm-quaddec

[Arnout Vandecappelle]

 [Full disclosure: I'm a colleague of Patrick.]

On 2019-03-16 14:21:38, Jonathan Cameron wrote:

> On Tue, 12 Mar 2019 14:09:52 -0500
> Rob Herring <robh@kernel.org> wrote:
>
> > On Wed, Mar 06, 2019 at 12:12:05PM +0100, Patrick Havelange wrote:
> > > FlexTimer quadrature decoder driver.
> > > 
> > > Signed-off-by: Patrick Havelange <patrick.havelange@essensium.com>
> > > Reviewed-by: Esben Haabendal <esben@haabendal.dk>
> > > ---
> > > Changes v2
> > > - None
> > > ---
> > > .../bindings/counter/ftm-quaddec.txt           | 18 ++++++++++++++++++
> > > 1 file changed, 18 insertions(+)
> > > create mode 100644 Documentation/devicetree/bindings/counter/ftm-quaddec.txt
> > > 
> > > diff --git a/Documentation/devicetree/bindings/counter/ftm-quaddec.txt \
> > > b/Documentation/devicetree/bindings/counter/ftm-quaddec.txt new file mode 100644
> > > index 000000000000..4d18cd722074
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/counter/ftm-quaddec.txt
> > > @@ -0,0 +1,18 @@
> > > +FlexTimer Quadrature decoder counter
> > > +
> > > +This driver exposes a simple counter for the quadrature decoder mode.  
> > 
> > Seems like this is more a mode of a h/w block than describing a h/w 
> > block. Bindings should do the latter.


  As Jonathan writes below, it really is a "hardware mode", since it is tied
very closely to how the device is wired up.

 Basically, the same block can be used for pretty diverse functions: a PWM where
the pins are output, a counter where the pins are input, or a timer where the
interrupt or timer value is used purely internally.

 This smells a bit like an MFD, but IMO it really isn't, because only one of the
functions can be enabled. So indeed, it's more like a mode.


> The snag is that we need to dig ourselves out of the hole set by:
> fsl,vf610-ftm-pwm etc.
>
> Documentation/devicetree/bindings/pwm/pwm-fsl-ftm.txt
> Documentation/devicetree/bindings/timer/fsl,ftm-timer.txt
> (I'm assuming these are the same IP block).
>
> Can probably be sorted out though.  One core driver binds against the
> ftm and deals with instantiating the others depending on the configuration
> (note that this mode for instance does make sense in DT as it's
> really reflecting the fact there is a quadrature encoder
> connected to the ftm).
>
> Fiddly though :)


 The way I see it, there are 3 ways this could be modelled (other than the
current way: several nodes with the same address).


1. The SoC's .dtsi defines a single node, and the compatible string (which would
be defined by the board .dts) both enables the node and sets the compatible
string. The .dtsi would also define the static properties of all the different
functions: some "static" properties, e.g. reg, but also some function
specific-properties, e.g.#pwm-cells (only for PWM), interrupts (only for timer).
The driver (selected through compatible) anyway only uses the properties that it
needs, so it doesn't hurt to have those other-function properties there.


2. Like 1, but instead of defining the compatible string in the .dts, use a
single compatible string for all the different drivers which is set in the
.dtsi, and add a mode property (to be set in the .dts) to select the driver. The
selection can be done either by having a top-level driver that calls out to the
subsystem-specific one based on the mode, or by having each driver bail out of
its probe function if the mode is not as expected.


3. Have a common node that essentially does nothing except occupy the memory
resource, and sub-nodes for each function. This can again be combined with a
common driver that does the common resource allocation, or each function driver
can just look at its parent node to find the resources. A disadvantage of this
one is that it is possible to enable several functions in the DT, while only one
can actually work.


 Option 3 is what is used for e.g. stm32-lptimer. It also uses an mfd driver to
model the common part. But possibly it actually allows the different functions
to operate simultaneously.


 Option 3 has the additional disadvantage that it requires changes in existing
DTs for ftm-pwm and ftm-timer, because some properties are moved one level down.
Since we need to retain backward compatibility, we'd need to look for those
properties both in the node itself and in the parent node. In particular, the
common driver part would be fairly complicated to implement in a backward
compatible way because it's not enough to do a simple devm_of_platform_populate().


 Personally I don't like the common driver part too much. This common driver
does almost nothing (iomap and clock) and it creates dependencies between
different drivers. Combined with the backward compatibility problem, I don't see
much point to it.


 I personally like option 2 the most. It's easy to be backward compatible (if
mode is not set, revert to the current behaviour, i.e. assume that the
compatible string has encoded the mode and that you're the only driver). It
doesn't introduce subnodes that have no hardware equivalent. The only messy
thing about it is that properties belonging to the different modes are mixed
together in a single node. And also, I don't think this kind of model is
currently used anywhere else in the kernel.



 Regards,
 Arnout

Re: [PATCH v2 4/7] dt-bindings: counter: ftm-quaddec

[Rob Herring]

On Tue, Mar 26, 2019 at 10:43 AM Arnout Vandecappelle <arnout@mind.be> wrote:
>
>  [Full disclosure: I'm a colleague of Patrick.]
>
> On 2019-03-16 14:21:38, Jonathan Cameron wrote:
>
> > On Tue, 12 Mar 2019 14:09:52 -0500
> > Rob Herring <robh@kernel.org> wrote:
> >
> > > On Wed, Mar 06, 2019 at 12:12:05PM +0100, Patrick Havelange wrote:
> > > > FlexTimer quadrature decoder driver.
> > > >
> > > > Signed-off-by: Patrick Havelange <patrick.havelange@essensium.com>
> > > > Reviewed-by: Esben Haabendal <esben@haabendal.dk>
> > > > ---
> > > > Changes v2
> > > > - None
> > > > ---
> > > > .../bindings/counter/ftm-quaddec.txt           | 18 ++++++++++++++++++
> > > > 1 file changed, 18 insertions(+)
> > > > create mode 100644 Documentation/devicetree/bindings/counter/ftm-quaddec.txt
> > > >
> > > > diff --git a/Documentation/devicetree/bindings/counter/ftm-quaddec.txt \
> > > > b/Documentation/devicetree/bindings/counter/ftm-quaddec.txt new file mode 100644
> > > > index 000000000000..4d18cd722074
> > > > --- /dev/null
> > > > +++ b/Documentation/devicetree/bindings/counter/ftm-quaddec.txt
> > > > @@ -0,0 +1,18 @@
> > > > +FlexTimer Quadrature decoder counter
> > > > +
> > > > +This driver exposes a simple counter for the quadrature decoder mode.
> > >
> > > Seems like this is more a mode of a h/w block than describing a h/w
> > > block. Bindings should do the latter.
>
>
>   As Jonathan writes below, it really is a "hardware mode", since it is tied
> very closely to how the device is wired up.

Okay, as it is describing what is attached, I agree.

The thing to consider is whether you will need to describe more than
just the mode. We often start adding properties of an attached device
in the controller node only to realize later that we should have a
node for the device itself. Even for something as simple as an LED
we've ended up there.

>  Basically, the same block can be used for pretty diverse functions: a PWM where
> the pins are output, a counter where the pins are input, or a timer where the
> interrupt or timer value is used purely internally.
>
>  This smells a bit like an MFD, but IMO it really isn't, because only one of the
> functions can be enabled. So indeed, it's more like a mode.

Agreed.

> > The snag is that we need to dig ourselves out of the hole set by:
> > fsl,vf610-ftm-pwm etc.
> >
> > Documentation/devicetree/bindings/pwm/pwm-fsl-ftm.txt
> > Documentation/devicetree/bindings/timer/fsl,ftm-timer.txt
> > (I'm assuming these are the same IP block).
> >
> > Can probably be sorted out though.  One core driver binds against the
> > ftm and deals with instantiating the others depending on the configuration
> > (note that this mode for instance does make sense in DT as it's
> > really reflecting the fact there is a quadrature encoder
> > connected to the ftm).
> >
> > Fiddly though :)
>
>
>  The way I see it, there are 3 ways this could be modelled (other than the
> current way: several nodes with the same address).
>
>
> 1. The SoC's .dtsi defines a single node, and the compatible string (which would
> be defined by the board .dts) both enables the node and sets the compatible
> string. The .dtsi would also define the static properties of all the different
> functions: some "static" properties, e.g. reg, but also some function
> specific-properties, e.g.#pwm-cells (only for PWM), interrupts (only for timer).
> The driver (selected through compatible) anyway only uses the properties that it
> needs, so it doesn't hurt to have those other-function properties there.
>
>
> 2. Like 1, but instead of defining the compatible string in the .dts, use a
> single compatible string for all the different drivers which is set in the
> .dtsi, and add a mode property (to be set in the .dts) to select the driver. The
> selection can be done either by having a top-level driver that calls out to the
> subsystem-specific one based on the mode, or by having each driver bail out of
> its probe function if the mode is not as expected.
>
>
> 3. Have a common node that essentially does nothing except occupy the memory
> resource, and sub-nodes for each function. This can again be combined with a
> common driver that does the common resource allocation, or each function driver
> can just look at its parent node to find the resources. A disadvantage of this
> one is that it is possible to enable several functions in the DT, while only one
> can actually work.
>
>
>  Option 3 is what is used for e.g. stm32-lptimer. It also uses an mfd driver to
> model the common part. But possibly it actually allows the different functions
> to operate simultaneously.

I'm not all that thrilled with how that one ended up.

>  Option 3 has the additional disadvantage that it requires changes in existing
> DTs for ftm-pwm and ftm-timer, because some properties are moved one level down.
> Since we need to retain backward compatibility, we'd need to look for those
> properties both in the node itself and in the parent node. In particular, the
> common driver part would be fairly complicated to implement in a backward
> compatible way because it's not enough to do a simple devm_of_platform_populate().
>
>
>  Personally I don't like the common driver part too much. This common driver
> does almost nothing (iomap and clock) and it creates dependencies between
> different drivers. Combined with the backward compatibility problem, I don't see
> much point to it.
>
>
>  I personally like option 2 the most. It's easy to be backward compatible (if
> mode is not set, revert to the current behaviour, i.e. assume that the
> compatible string has encoded the mode and that you're the only driver). It
> doesn't introduce subnodes that have no hardware equivalent. The only messy
> thing about it is that properties belonging to the different modes are mixed
> together in a single node. And also, I don't think this kind of model is
> currently used anywhere else in the kernel.

Option 2 seems best to me.

Rob

[PATCH v2 5/7] counter: add FlexTimer Module Quadrature decoder counter driver

[Patrick Havelange]

This driver exposes the counter for the quadrature decoder of the
FlexTimer Module, present in the LS1021A soc.

Signed-off-by: Patrick Havelange <patrick.havelange@essensium.com>
---
Changes v2
 - Rebased on new counter subsystem
 - Cleaned up included headers
 - Use devm_ioremap()
 - Correct order of devm_ and unmanaged resources
---
 drivers/counter/Kconfig       |   9 +
 drivers/counter/Makefile      |   1 +
 drivers/counter/ftm-quaddec.c | 356 ++++++++++++++++++++++++++++++++++
 3 files changed, 366 insertions(+)
 create mode 100644 drivers/counter/ftm-quaddec.c

diff --git a/drivers/counter/Kconfig b/drivers/counter/Kconfig
index 87c491a19c63..233ac305d878 100644
--- a/drivers/counter/Kconfig
+++ b/drivers/counter/Kconfig
@@ -48,4 +48,13 @@ config STM32_LPTIMER_CNT
 	  To compile this driver as a module, choose M here: the
 	  module will be called stm32-lptimer-cnt.
 
+config FTM_QUADDEC
+	tristate "Flex Timer Module Quadrature decoder driver"
+	help
+	  Select this option to enable the Flex Timer Quadrature decoder
+	  driver.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ftm-quaddec.
+
 endif # COUNTER
diff --git a/drivers/counter/Makefile b/drivers/counter/Makefile
index 5589976d37f8..0c9e622a6bea 100644
--- a/drivers/counter/Makefile
+++ b/drivers/counter/Makefile
@@ -7,3 +7,4 @@ obj-$(CONFIG_COUNTER) += counter.o
 obj-$(CONFIG_104_QUAD_8)	+= 104-quad-8.o
 obj-$(CONFIG_STM32_TIMER_CNT)	+= stm32-timer-cnt.o
 obj-$(CONFIG_STM32_LPTIMER_CNT)	+= stm32-lptimer-cnt.o
+obj-$(CONFIG_FTM_QUADDEC)	+= ftm-quaddec.o
diff --git a/drivers/counter/ftm-quaddec.c b/drivers/counter/ftm-quaddec.c
new file mode 100644
index 000000000000..1bc9e075a386
--- /dev/null
+++ b/drivers/counter/ftm-quaddec.c
@@ -0,0 +1,356 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Flex Timer Module Quadrature decoder
+ *
+ * This module implements a driver for decoding the FTM quadrature
+ * of ex. a LS1021A
+ */
+
+#include <linux/fsl/ftm.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/io.h>
+#include <linux/mutex.h>
+#include <linux/counter.h>
+
+struct ftm_quaddec {
+	struct counter_device counter;
+	struct platform_device *pdev;
+	void __iomem *ftm_base;
+	bool big_endian;
+	struct mutex ftm_quaddec_mutex;
+};
+
+static void ftm_read(struct ftm_quaddec *ftm, uint32_t offset, uint32_t *data)
+{
+	if (ftm->big_endian)
+		*data = ioread32be(ftm->ftm_base + offset);
+	else
+		*data = ioread32(ftm->ftm_base + offset);
+}
+
+static void ftm_write(struct ftm_quaddec *ftm, uint32_t offset, uint32_t data)
+{
+	if (ftm->big_endian)
+		iowrite32be(data, ftm->ftm_base + offset);
+	else
+		iowrite32(data, ftm->ftm_base + offset);
+}
+
+/*
+ * take mutex
+ * call ftm_clear_write_protection
+ * update settings
+ * call ftm_set_write_protection
+ * release mutex
+ */
+static void ftm_clear_write_protection(struct ftm_quaddec *ftm)
+{
+	uint32_t flag;
+
+	/* First see if it is enabled */
+	ftm_read(ftm, FTM_FMS, &flag);
+
+	if (flag & FTM_FMS_WPEN) {
+		ftm_read(ftm, FTM_MODE, &flag);
+		ftm_write(ftm, FTM_MODE, flag | FTM_MODE_WPDIS);
+	}
+}
+
+static void ftm_set_write_protection(struct ftm_quaddec *ftm)
+{
+	ftm_write(ftm, FTM_FMS, FTM_FMS_WPEN);
+}
+
+static void ftm_reset_counter(struct ftm_quaddec *ftm)
+{
+	/* Reset hardware counter to CNTIN */
+	ftm_write(ftm, FTM_CNT, 0x0);
+}
+
+static void ftm_quaddec_init(struct ftm_quaddec *ftm)
+{
+	ftm_clear_write_protection(ftm);
+
+	/*
+	 * Do not write in the region from the CNTIN register through the
+	 * PWMLOAD register when FTMEN = 0.
+	 */
+	ftm_write(ftm, FTM_MODE, FTM_MODE_FTMEN);
+	ftm_write(ftm, FTM_CNTIN, 0x0000);
+	ftm_write(ftm, FTM_MOD, 0xffff);
+	ftm_write(ftm, FTM_CNT, 0x0);
+	ftm_write(ftm, FTM_SC, FTM_SC_PS_1);
+
+	/* Select quad mode */
+	ftm_write(ftm, FTM_QDCTRL, FTM_QDCTRL_QUADEN);
+
+	/* Unused features and reset to default section */
+	ftm_write(ftm, FTM_POL, 0x0);
+	ftm_write(ftm, FTM_FLTCTRL, 0x0);
+	ftm_write(ftm, FTM_SYNCONF, 0x0);
+	ftm_write(ftm, FTM_SYNC, 0xffff);
+
+	/* Lock the FTM */
+	ftm_set_write_protection(ftm);
+}
+
+static void ftm_quaddec_disable(struct ftm_quaddec *ftm)
+{
+	ftm_write(ftm, FTM_MODE, 0);
+}
+
+static int ftm_quaddec_get_prescaler(struct counter_device *counter,
+				     struct counter_count *count,
+				     size_t *cnt_mode)
+{
+	struct ftm_quaddec *ftm = counter->priv;
+	uint32_t scflags;
+
+	ftm_read(ftm, FTM_SC, &scflags);
+
+	*cnt_mode = scflags & FTM_SC_PS_MASK;
+
+	return 0;
+}
+
+static int ftm_quaddec_set_prescaler(struct counter_device *counter,
+				     struct counter_count *count,
+				     size_t cnt_mode)
+{
+	struct ftm_quaddec *ftm = counter->priv;
+
+	uint32_t scflags;
+
+	mutex_lock(&ftm->ftm_quaddec_mutex);
+
+	ftm_read(ftm, FTM_SC, &scflags);
+
+	scflags &= ~FTM_SC_PS_MASK;
+	cnt_mode &= FTM_SC_PS_MASK; /*just to be 100% sure*/
+
+	scflags |= cnt_mode;
+
+	/* Write */
+	ftm_clear_write_protection(ftm);
+	ftm_write(ftm, FTM_SC, scflags);
+	ftm_set_write_protection(ftm);
+
+	/* Also resets the counter as it is undefined anyway now */
+	ftm_reset_counter(ftm);
+
+	mutex_unlock(&ftm->ftm_quaddec_mutex);
+	return 0;
+}
+
+static const char * const ftm_quaddec_prescaler[] = {
+	"1", "2", "4", "8", "16", "32", "64", "128"
+};
+
+static struct counter_count_enum_ext ftm_quaddec_prescaler_enum = {
+	.items = ftm_quaddec_prescaler,
+	.num_items = ARRAY_SIZE(ftm_quaddec_prescaler),
+	.get = ftm_quaddec_get_prescaler,
+	.set = ftm_quaddec_set_prescaler
+};
+
+enum ftm_quaddec_synapse_action {
+	FTM_QUADDEC_SYNAPSE_ACTION_BOTH_EDGES,
+};
+
+static enum counter_synapse_action ftm_quaddec_synapse_actions[] = {
+	[FTM_QUADDEC_SYNAPSE_ACTION_BOTH_EDGES] =
+	COUNTER_SYNAPSE_ACTION_BOTH_EDGES
+};
+
+enum ftm_quaddec_count_function {
+	FTM_QUADDEC_COUNT_ENCODER_MODE_1,
+};
+
+static const enum counter_count_function ftm_quaddec_count_functions[] = {
+	[FTM_QUADDEC_COUNT_ENCODER_MODE_1] =
+	COUNTER_COUNT_FUNCTION_QUADRATURE_X4
+};
+
+static int ftm_quaddec_count_read(struct counter_device *counter,
+				  struct counter_count *count,
+				  struct counter_count_read_value *val)
+{
+	struct ftm_quaddec *const ftm = counter->priv;
+	uint32_t cntval;
+
+	ftm_read(ftm, FTM_CNT, &cntval);
+
+	counter_count_read_value_set(val, COUNTER_COUNT_POSITION, &cntval);
+
+	return 0;
+}
+
+static int ftm_quaddec_count_write(struct counter_device *counter,
+				   struct counter_count *count,
+				   struct counter_count_write_value *val)
+{
+	struct ftm_quaddec *const ftm = counter->priv;
+	u32 cnt;
+	int err;
+
+	err = counter_count_write_value_get(&cnt, COUNTER_COUNT_POSITION, val);
+	if (err)
+		return err;
+
+	if (cnt != 0) {
+		dev_warn(&ftm->pdev->dev, "Can only accept '0' as new counter value\n");
+		return -EINVAL;
+	}
+
+	ftm_reset_counter(ftm);
+
+	return 0;
+}
+
+static int ftm_quaddec_count_function_get(struct counter_device *counter,
+					  struct counter_count *count,
+					  size_t *function)
+{
+	*function = FTM_QUADDEC_COUNT_ENCODER_MODE_1;
+
+	return 0;
+}
+
+static int ftm_quaddec_action_get(struct counter_device *counter,
+				  struct counter_count *count,
+				  struct counter_synapse *synapse,
+				  size_t *action)
+{
+	*action = FTM_QUADDEC_SYNAPSE_ACTION_BOTH_EDGES;
+
+	return 0;
+}
+
+static const struct counter_ops ftm_quaddec_cnt_ops = {
+	.count_read = ftm_quaddec_count_read,
+	.count_write = ftm_quaddec_count_write,
+	.function_get = ftm_quaddec_count_function_get,
+	.action_get = ftm_quaddec_action_get,
+};
+
+static struct counter_signal ftm_quaddec_signals[] = {
+	{
+		.id = 0,
+		.name = "Channel 1 Quadrature A"
+	},
+	{
+		.id = 1,
+		.name = "Channel 1 Quadrature B"
+	}
+};
+
+static struct counter_synapse ftm_quaddec_count_synapses[] = {
+	{
+		.actions_list = ftm_quaddec_synapse_actions,
+		.num_actions = ARRAY_SIZE(ftm_quaddec_synapse_actions),
+		.signal = &ftm_quaddec_signals[0]
+	},
+	{
+		.actions_list = ftm_quaddec_synapse_actions,
+		.num_actions = ARRAY_SIZE(ftm_quaddec_synapse_actions),
+		.signal = &ftm_quaddec_signals[1]
+	}
+};
+
+static const struct counter_count_ext ftm_quaddec_count_ext[] = {
+	COUNTER_COUNT_ENUM("prescaler", &ftm_quaddec_prescaler_enum),
+	COUNTER_COUNT_ENUM_AVAILABLE("prescaler", &ftm_quaddec_prescaler_enum),
+};
+
+static struct counter_count ftm_quaddec_counts = {
+	.id = 0,
+	.name = "Channel 1 Count",
+	.functions_list = ftm_quaddec_count_functions,
+	.num_functions = ARRAY_SIZE(ftm_quaddec_count_functions),
+	.synapses = ftm_quaddec_count_synapses,
+	.num_synapses = ARRAY_SIZE(ftm_quaddec_count_synapses),
+	.ext = ftm_quaddec_count_ext,
+	.num_ext = ARRAY_SIZE(ftm_quaddec_count_ext)
+};
+
+static int ftm_quaddec_probe(struct platform_device *pdev)
+{
+	struct ftm_quaddec *ftm;
+
+	struct device_node *node = pdev->dev.of_node;
+	struct resource *io;
+	int ret;
+
+	ftm = devm_kzalloc(&pdev->dev, sizeof(*ftm), GFP_KERNEL);
+	if (!ftm)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, ftm);
+
+	io = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!io) {
+		dev_err(&pdev->dev, "Failed to get memory region\n");
+		return -ENODEV;
+	}
+
+	ftm->pdev = pdev;
+	ftm->big_endian = of_property_read_bool(node, "big-endian");
+	ftm->ftm_base = devm_ioremap(&pdev->dev, io->start, resource_size(io));
+
+	if (!ftm->ftm_base) {
+		dev_err(&pdev->dev, "Failed to map memory region\n");
+		return -EINVAL;
+	}
+	ftm->counter.name = dev_name(&pdev->dev);
+	ftm->counter.parent = &pdev->dev;
+	ftm->counter.ops = &ftm_quaddec_cnt_ops;
+	ftm->counter.counts = &ftm_quaddec_counts;
+	ftm->counter.num_counts = 1;
+	ftm->counter.signals = ftm_quaddec_signals;
+	ftm->counter.num_signals = ARRAY_SIZE(ftm_quaddec_signals);
+	ftm->counter.priv = ftm;
+
+	mutex_init(&ftm->ftm_quaddec_mutex);
+
+	ftm_quaddec_init(ftm);
+
+	ret = counter_register(&ftm->counter);
+	if (ret)
+		ftm_quaddec_disable(ftm);
+
+	return ret;
+}
+
+static int ftm_quaddec_remove(struct platform_device *pdev)
+{
+	struct ftm_quaddec *ftm = platform_get_drvdata(pdev);
+
+	counter_unregister(&ftm->counter);
+
+	ftm_quaddec_disable(ftm);
+
+	return 0;
+}
+
+static const struct of_device_id ftm_quaddec_match[] = {
+	{ .compatible = "fsl,ftm-quaddec" },
+	{},
+};
+
+static struct platform_driver ftm_quaddec_driver = {
+	.driver = {
+		.name = "ftm-quaddec",
+		.owner = THIS_MODULE,
+		.of_match_table = ftm_quaddec_match,
+	},
+	.probe = ftm_quaddec_probe,
+	.remove = ftm_quaddec_remove,
+};
+
+module_platform_driver(ftm_quaddec_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Kjeld Flarup <kfa@deif.com");
+MODULE_AUTHOR("Patrick Havelange <patrick.havelange@essensium.com");
-- 
2.19.1

Re: [PATCH v2 5/7] counter: add FlexTimer Module Quadrature decoder counter driver

[William Breathitt Gray]

On Wed, Mar 06, 2019 at 12:12:06PM +0100, Patrick Havelange wrote:
> This driver exposes the counter for the quadrature decoder of the
> FlexTimer Module, present in the LS1021A soc.
> 
> Signed-off-by: Patrick Havelange <patrick.havelange@essensium.com>
> ---
> Changes v2
>  - Rebased on new counter subsystem
>  - Cleaned up included headers
>  - Use devm_ioremap()
>  - Correct order of devm_ and unmanaged resources
> ---
>  drivers/counter/Kconfig       |   9 +
>  drivers/counter/Makefile      |   1 +
>  drivers/counter/ftm-quaddec.c | 356 ++++++++++++++++++++++++++++++++++
>  3 files changed, 366 insertions(+)
>  create mode 100644 drivers/counter/ftm-quaddec.c

Overall, I think you utilized the Generic Counter interface correctly.
So good job on the conversion from your initial patch. :-)

Some minor inline suggestions/comments follow.

> 
> diff --git a/drivers/counter/Kconfig b/drivers/counter/Kconfig
> index 87c491a19c63..233ac305d878 100644
> --- a/drivers/counter/Kconfig
> +++ b/drivers/counter/Kconfig
> @@ -48,4 +48,13 @@ config STM32_LPTIMER_CNT
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called stm32-lptimer-cnt.
>  
> +config FTM_QUADDEC
> +	tristate "Flex Timer Module Quadrature decoder driver"
> +	help
> +	  Select this option to enable the Flex Timer Quadrature decoder
> +	  driver.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called ftm-quaddec.
> +
>  endif # COUNTER
> diff --git a/drivers/counter/Makefile b/drivers/counter/Makefile
> index 5589976d37f8..0c9e622a6bea 100644
> --- a/drivers/counter/Makefile
> +++ b/drivers/counter/Makefile
> @@ -7,3 +7,4 @@ obj-$(CONFIG_COUNTER) += counter.o
>  obj-$(CONFIG_104_QUAD_8)	+= 104-quad-8.o
>  obj-$(CONFIG_STM32_TIMER_CNT)	+= stm32-timer-cnt.o
>  obj-$(CONFIG_STM32_LPTIMER_CNT)	+= stm32-lptimer-cnt.o
> +obj-$(CONFIG_FTM_QUADDEC)	+= ftm-quaddec.o
> diff --git a/drivers/counter/ftm-quaddec.c b/drivers/counter/ftm-quaddec.c
> new file mode 100644
> index 000000000000..1bc9e075a386
> --- /dev/null
> +++ b/drivers/counter/ftm-quaddec.c
> @@ -0,0 +1,356 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Flex Timer Module Quadrature decoder
> + *
> + * This module implements a driver for decoding the FTM quadrature
> + * of ex. a LS1021A
> + */
> +
> +#include <linux/fsl/ftm.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/of.h>
> +#include <linux/io.h>
> +#include <linux/mutex.h>
> +#include <linux/counter.h>
> +
> +struct ftm_quaddec {
> +	struct counter_device counter;
> +	struct platform_device *pdev;
> +	void __iomem *ftm_base;
> +	bool big_endian;
> +	struct mutex ftm_quaddec_mutex;
> +};
> +
> +static void ftm_read(struct ftm_quaddec *ftm, uint32_t offset, uint32_t *data)
> +{
> +	if (ftm->big_endian)
> +		*data = ioread32be(ftm->ftm_base + offset);
> +	else
> +		*data = ioread32(ftm->ftm_base + offset);
> +}
> +
> +static void ftm_write(struct ftm_quaddec *ftm, uint32_t offset, uint32_t data)
> +{
> +	if (ftm->big_endian)
> +		iowrite32be(data, ftm->ftm_base + offset);
> +	else
> +		iowrite32(data, ftm->ftm_base + offset);
> +}
> +
> +/*
> + * take mutex
> + * call ftm_clear_write_protection
> + * update settings
> + * call ftm_set_write_protection
> + * release mutex
> + */

Jonathan mentioned it before in the previous review, and I think I agree
too, that this comment block is superfluous: the context of this code is
simple enough that the function call order is naturally obvious (i.e.
write protection must be cleared before settings are modified).

The only important thing to mention here is that the mutex must be held
before the write protection state is modified so a comment along the
following lines should suffice:

/* hold mutex before modifying write protection state */

> +static void ftm_clear_write_protection(struct ftm_quaddec *ftm)
> +{
> +	uint32_t flag;
> +
> +	/* First see if it is enabled */
> +	ftm_read(ftm, FTM_FMS, &flag);
> +
> +	if (flag & FTM_FMS_WPEN) {
> +		ftm_read(ftm, FTM_MODE, &flag);
> +		ftm_write(ftm, FTM_MODE, flag | FTM_MODE_WPDIS);
> +	}
> +}
> +
> +static void ftm_set_write_protection(struct ftm_quaddec *ftm)
> +{
> +	ftm_write(ftm, FTM_FMS, FTM_FMS_WPEN);
> +}
> +
> +static void ftm_reset_counter(struct ftm_quaddec *ftm)
> +{
> +	/* Reset hardware counter to CNTIN */
> +	ftm_write(ftm, FTM_CNT, 0x0);
> +}
> +
> +static void ftm_quaddec_init(struct ftm_quaddec *ftm)
> +{
> +	ftm_clear_write_protection(ftm);
> +
> +	/*
> +	 * Do not write in the region from the CNTIN register through the
> +	 * PWMLOAD register when FTMEN = 0.
> +	 */
> +	ftm_write(ftm, FTM_MODE, FTM_MODE_FTMEN);
> +	ftm_write(ftm, FTM_CNTIN, 0x0000);
> +	ftm_write(ftm, FTM_MOD, 0xffff);
> +	ftm_write(ftm, FTM_CNT, 0x0);
> +	ftm_write(ftm, FTM_SC, FTM_SC_PS_1);
> +
> +	/* Select quad mode */
> +	ftm_write(ftm, FTM_QDCTRL, FTM_QDCTRL_QUADEN);
> +
> +	/* Unused features and reset to default section */
> +	ftm_write(ftm, FTM_POL, 0x0);
> +	ftm_write(ftm, FTM_FLTCTRL, 0x0);
> +	ftm_write(ftm, FTM_SYNCONF, 0x0);
> +	ftm_write(ftm, FTM_SYNC, 0xffff);
> +
> +	/* Lock the FTM */
> +	ftm_set_write_protection(ftm);
> +}
> +
> +static void ftm_quaddec_disable(struct ftm_quaddec *ftm)
> +{
> +	ftm_write(ftm, FTM_MODE, 0);
> +}

The ftm_quaddec_disable function is only used for cleanup when the
driver is being removed. Is disabling the FTM counter on removal
actually something we need to do?

While it's true that the register will keep updating, since the driver
is no longer loaded, we don't care about that register value. Once we
take control of the hardware again (by reloading our driver or via a new
one), we reinitialize the counter and set the count value back to 0
anyway -- so whatever value the register had no longer matters.

> +
> +static int ftm_quaddec_get_prescaler(struct counter_device *counter,
> +				     struct counter_count *count,
> +				     size_t *cnt_mode)
> +{
> +	struct ftm_quaddec *ftm = counter->priv;
> +	uint32_t scflags;
> +
> +	ftm_read(ftm, FTM_SC, &scflags);
> +
> +	*cnt_mode = scflags & FTM_SC_PS_MASK;
> +
> +	return 0;
> +}
> +
> +static int ftm_quaddec_set_prescaler(struct counter_device *counter,
> +				     struct counter_count *count,
> +				     size_t cnt_mode)
> +{
> +	struct ftm_quaddec *ftm = counter->priv;
> +
> +	uint32_t scflags;
> +
> +	mutex_lock(&ftm->ftm_quaddec_mutex);
> +
> +	ftm_read(ftm, FTM_SC, &scflags);
> +
> +	scflags &= ~FTM_SC_PS_MASK;
> +	cnt_mode &= FTM_SC_PS_MASK; /*just to be 100% sure*/
> +
> +	scflags |= cnt_mode;
> +
> +	/* Write */
> +	ftm_clear_write_protection(ftm);
> +	ftm_write(ftm, FTM_SC, scflags);
> +	ftm_set_write_protection(ftm);
> +
> +	/* Also resets the counter as it is undefined anyway now */
> +	ftm_reset_counter(ftm);
> +
> +	mutex_unlock(&ftm->ftm_quaddec_mutex);
> +	return 0;
> +}
> +
> +static const char * const ftm_quaddec_prescaler[] = {
> +	"1", "2", "4", "8", "16", "32", "64", "128"
> +};
> +
> +static struct counter_count_enum_ext ftm_quaddec_prescaler_enum = {
> +	.items = ftm_quaddec_prescaler,
> +	.num_items = ARRAY_SIZE(ftm_quaddec_prescaler),
> +	.get = ftm_quaddec_get_prescaler,
> +	.set = ftm_quaddec_set_prescaler
> +};
> +
> +enum ftm_quaddec_synapse_action {
> +	FTM_QUADDEC_SYNAPSE_ACTION_BOTH_EDGES,
> +};
> +
> +static enum counter_synapse_action ftm_quaddec_synapse_actions[] = {
> +	[FTM_QUADDEC_SYNAPSE_ACTION_BOTH_EDGES] =
> +	COUNTER_SYNAPSE_ACTION_BOTH_EDGES
> +};
> +
> +enum ftm_quaddec_count_function {
> +	FTM_QUADDEC_COUNT_ENCODER_MODE_1,
> +};

The FlexTimer Module supports more than just a quadrature counter mode
doesn't it?

We should keep this initial patch simple since we are still introducing
the Counter subsystem, but it'll be nice to add support in the future
for the other counter modes such as single-edge capture.

> +
> +static const enum counter_count_function ftm_quaddec_count_functions[] = {
> +	[FTM_QUADDEC_COUNT_ENCODER_MODE_1] =
> +	COUNTER_COUNT_FUNCTION_QUADRATURE_X4
> +};
> +
> +static int ftm_quaddec_count_read(struct counter_device *counter,
> +				  struct counter_count *count,
> +				  struct counter_count_read_value *val)
> +{
> +	struct ftm_quaddec *const ftm = counter->priv;
> +	uint32_t cntval;
> +
> +	ftm_read(ftm, FTM_CNT, &cntval);
> +
> +	counter_count_read_value_set(val, COUNTER_COUNT_POSITION, &cntval);
> +
> +	return 0;
> +}
> +
> +static int ftm_quaddec_count_write(struct counter_device *counter,
> +				   struct counter_count *count,
> +				   struct counter_count_write_value *val)
> +{
> +	struct ftm_quaddec *const ftm = counter->priv;
> +	u32 cnt;
> +	int err;
> +
> +	err = counter_count_write_value_get(&cnt, COUNTER_COUNT_POSITION, val);
> +	if (err)
> +		return err;
> +
> +	if (cnt != 0) {
> +		dev_warn(&ftm->pdev->dev, "Can only accept '0' as new counter value\n");
> +		return -EINVAL;
> +	}
> +
> +	ftm_reset_counter(ftm);
> +
> +	return 0;
> +}
> +
> +static int ftm_quaddec_count_function_get(struct counter_device *counter,
> +					  struct counter_count *count,
> +					  size_t *function)
> +{
> +	*function = FTM_QUADDEC_COUNT_ENCODER_MODE_1;
> +
> +	return 0;
> +}
> +
> +static int ftm_quaddec_action_get(struct counter_device *counter,
> +				  struct counter_count *count,
> +				  struct counter_synapse *synapse,
> +				  size_t *action)
> +{
> +	*action = FTM_QUADDEC_SYNAPSE_ACTION_BOTH_EDGES;
> +
> +	return 0;
> +}
> +
> +static const struct counter_ops ftm_quaddec_cnt_ops = {
> +	.count_read = ftm_quaddec_count_read,
> +	.count_write = ftm_quaddec_count_write,
> +	.function_get = ftm_quaddec_count_function_get,
> +	.action_get = ftm_quaddec_action_get,
> +};
> +
> +static struct counter_signal ftm_quaddec_signals[] = {
> +	{
> +		.id = 0,
> +		.name = "Channel 1 Quadrature A"
> +	},
> +	{
> +		.id = 1,
> +		.name = "Channel 1 Quadrature B"
> +	}
> +};

If possible, these names should match the FTM datasheet naming
convention. The reason is to make it easier for users to match the
input signals described in the datasheet with the Signal data provided
by the Generic Counter interface.

I think the FTM datasheet describes these signals as "Phase A" and
"Phase B", so perhaps "Channel 1 Phase A" and "Channel 1 Phase B" may be
more appropriate names in this case.

> +
> +static struct counter_synapse ftm_quaddec_count_synapses[] = {
> +	{
> +		.actions_list = ftm_quaddec_synapse_actions,
> +		.num_actions = ARRAY_SIZE(ftm_quaddec_synapse_actions),
> +		.signal = &ftm_quaddec_signals[0]
> +	},
> +	{
> +		.actions_list = ftm_quaddec_synapse_actions,
> +		.num_actions = ARRAY_SIZE(ftm_quaddec_synapse_actions),
> +		.signal = &ftm_quaddec_signals[1]
> +	}
> +};
> +
> +static const struct counter_count_ext ftm_quaddec_count_ext[] = {
> +	COUNTER_COUNT_ENUM("prescaler", &ftm_quaddec_prescaler_enum),
> +	COUNTER_COUNT_ENUM_AVAILABLE("prescaler", &ftm_quaddec_prescaler_enum),
> +};
> +
> +static struct counter_count ftm_quaddec_counts = {
> +	.id = 0,
> +	.name = "Channel 1 Count",
> +	.functions_list = ftm_quaddec_count_functions,
> +	.num_functions = ARRAY_SIZE(ftm_quaddec_count_functions),
> +	.synapses = ftm_quaddec_count_synapses,
> +	.num_synapses = ARRAY_SIZE(ftm_quaddec_count_synapses),
> +	.ext = ftm_quaddec_count_ext,
> +	.num_ext = ARRAY_SIZE(ftm_quaddec_count_ext)
> +};
> +
> +static int ftm_quaddec_probe(struct platform_device *pdev)
> +{
> +	struct ftm_quaddec *ftm;
> +
> +	struct device_node *node = pdev->dev.of_node;
> +	struct resource *io;
> +	int ret;
> +
> +	ftm = devm_kzalloc(&pdev->dev, sizeof(*ftm), GFP_KERNEL);
> +	if (!ftm)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, ftm);
> +
> +	io = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!io) {
> +		dev_err(&pdev->dev, "Failed to get memory region\n");
> +		return -ENODEV;
> +	}
> +
> +	ftm->pdev = pdev;
> +	ftm->big_endian = of_property_read_bool(node, "big-endian");
> +	ftm->ftm_base = devm_ioremap(&pdev->dev, io->start, resource_size(io));
> +
> +	if (!ftm->ftm_base) {
> +		dev_err(&pdev->dev, "Failed to map memory region\n");
> +		return -EINVAL;
> +	}
> +	ftm->counter.name = dev_name(&pdev->dev);
> +	ftm->counter.parent = &pdev->dev;
> +	ftm->counter.ops = &ftm_quaddec_cnt_ops;
> +	ftm->counter.counts = &ftm_quaddec_counts;
> +	ftm->counter.num_counts = 1;
> +	ftm->counter.signals = ftm_quaddec_signals;
> +	ftm->counter.num_signals = ARRAY_SIZE(ftm_quaddec_signals);
> +	ftm->counter.priv = ftm;
> +
> +	mutex_init(&ftm->ftm_quaddec_mutex);
> +
> +	ftm_quaddec_init(ftm);
> +
> +	ret = counter_register(&ftm->counter);
> +	if (ret)
> +		ftm_quaddec_disable(ftm);
> +
> +	return ret;
> +}
> +
> +static int ftm_quaddec_remove(struct platform_device *pdev)
> +{
> +	struct ftm_quaddec *ftm = platform_get_drvdata(pdev);
> +
> +	counter_unregister(&ftm->counter);
> +
> +	ftm_quaddec_disable(ftm);
> +
> +	return 0;
> +}

If the ftm_quaddec_disable is not necessary, then we can eliminate the
ftm_quaddec_remove function as well by replacing the counter_register
call with a devm_counter_register call.

William Breathitt Gray

> +
> +static const struct of_device_id ftm_quaddec_match[] = {
> +	{ .compatible = "fsl,ftm-quaddec" },
> +	{},
> +};
> +
> +static struct platform_driver ftm_quaddec_driver = {
> +	.driver = {
> +		.name = "ftm-quaddec",
> +		.owner = THIS_MODULE,
> +		.of_match_table = ftm_quaddec_match,
> +	},
> +	.probe = ftm_quaddec_probe,
> +	.remove = ftm_quaddec_remove,
> +};
> +
> +module_platform_driver(ftm_quaddec_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Kjeld Flarup <kfa@deif.com");
> +MODULE_AUTHOR("Patrick Havelange <patrick.havelange@essensium.com");
> -- 
> 2.19.1
> 

Re: [PATCH v2 5/7] counter: add FlexTimer Module Quadrature decoder counter driver

[Patrick Havelange]

On Thu, Mar 7, 2019 at 12:32 PM William Breathitt Gray
<vilhelm.gray@gmail.com> wrote:
> > +/*
> > + * take mutex
> > + * call ftm_clear_write_protection
> > + * update settings
> > + * call ftm_set_write_protection
> > + * release mutex
> > + */
>
> Jonathan mentioned it before in the previous review, and I think I agree
> too, that this comment block is superfluous: the context of this code is
> simple enough that the function call order is naturally obvious (i.e.
> write protection must be cleared before settings are modified).
>
> The only important thing to mention here is that the mutex must be held
> before the write protection state is modified so a comment along the
> following lines should suffice:
>
> /* hold mutex before modifying write protection state */

I think that keeping the more verbose comments is better. You directly see
what operations are needed, and is a good reminder, especially if you
are not familiar with the driver.
I'll use your comment on the next version if you insist (see below for
why new versoion).

> > +static void ftm_quaddec_disable(struct ftm_quaddec *ftm)
> > +{
> > +     ftm_write(ftm, FTM_MODE, 0);
> > +}
>
> The ftm_quaddec_disable function is only used for cleanup when the
> driver is being removed. Is disabling the FTM counter on removal
> actually something we need to do?

It might provide some power-saving, so I would keep that function.

>
> While it's true that the register will keep updating, since the driver
> is no longer loaded, we don't care about that register value. Once we
> take control of the hardware again (by reloading our driver or via a new
> one), we reinitialize the counter and set the count value back to 0
> anyway -- so whatever value the register had no longer matters.
>
Indeed the previous values at start do not matter. It's there just to
shut down the device properly.
This discussion made me verify again the specs and in its current form
the disable doesn't even work at all :
 - That register should be written with write protection disabled (duh!)
 - It doesn't even stop the FTM from running, the clock must be
disabled for that.

So I'll probably provide a fix for that (in some days/weeks).

> > +
> > +enum ftm_quaddec_count_function {
> > +     FTM_QUADDEC_COUNT_ENCODER_MODE_1,
> > +};
>
> The FlexTimer Module supports more than just a quadrature counter mode
> doesn't it?
>
> We should keep this initial patch simple since we are still introducing
> the Counter subsystem, but it'll be nice to add support in the future
> for the other counter modes such as single-edge capture.

yes it provides more features, those are in a backlog ;). I would
prefer if this simple version(I mean, with the disable/shutdown fixed)
of the driver could be merged already before extending support.

>
> > +
> > +static struct counter_signal ftm_quaddec_signals[] = {
> > +     {
> > +             .id = 0,
> > +             .name = "Channel 1 Quadrature A"
> > +     },
> > +     {
> > +             .id = 1,
> > +             .name = "Channel 1 Quadrature B"
> > +     }
> > +};
>
> If possible, these names should match the FTM datasheet naming
> convention. The reason is to make it easier for users to match the
> input signals described in the datasheet with the Signal data provided
> by the Generic Counter interface.
>
> I think the FTM datasheet describes these signals as "Phase A" and
> "Phase B", so perhaps "Channel 1 Phase A" and "Channel 1 Phase B" may be
> more appropriate names in this case.

I'll verify those,

> > +static int ftm_quaddec_remove(struct platform_device *pdev)
> > +{
> > +     struct ftm_quaddec *ftm = platform_get_drvdata(pdev);
> > +
> > +     counter_unregister(&ftm->counter);
> > +
> > +     ftm_quaddec_disable(ftm);
> > +
> > +     return 0;
> > +}
>
> If the ftm_quaddec_disable is not necessary, then we can eliminate the
> ftm_quaddec_remove function as well by replacing the counter_register
> call with a devm_counter_register call.

yes, but as stated before, I would keep it for potential energy saving.

Thanks for your feedback :)

Re: [PATCH v2 5/7] counter: add FlexTimer Module Quadrature decoder counter driver

[Jonathan Cameron]

On Wed, 6 Mar 2019 12:12:06 +0100
Patrick Havelange <patrick.havelange@essensium.com> wrote:

> This driver exposes the counter for the quadrature decoder of the
> FlexTimer Module, present in the LS1021A soc.
> 
> Signed-off-by: Patrick Havelange <patrick.havelange@essensium.com>
A few really trivial bits inline to add to William's feedback.

Otherwise I'm happy enough,

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
> Changes v2
>  - Rebased on new counter subsystem
>  - Cleaned up included headers
>  - Use devm_ioremap()
>  - Correct order of devm_ and unmanaged resources
> ---
>  drivers/counter/Kconfig       |   9 +
>  drivers/counter/Makefile      |   1 +
>  drivers/counter/ftm-quaddec.c | 356 ++++++++++++++++++++++++++++++++++
>  3 files changed, 366 insertions(+)
>  create mode 100644 drivers/counter/ftm-quaddec.c
> 
> diff --git a/drivers/counter/Kconfig b/drivers/counter/Kconfig
> index 87c491a19c63..233ac305d878 100644
> --- a/drivers/counter/Kconfig
> +++ b/drivers/counter/Kconfig
> @@ -48,4 +48,13 @@ config STM32_LPTIMER_CNT
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called stm32-lptimer-cnt.
>  
> +config FTM_QUADDEC
> +	tristate "Flex Timer Module Quadrature decoder driver"
> +	help
> +	  Select this option to enable the Flex Timer Quadrature decoder
> +	  driver.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called ftm-quaddec.
> +
>  endif # COUNTER
> diff --git a/drivers/counter/Makefile b/drivers/counter/Makefile
> index 5589976d37f8..0c9e622a6bea 100644
> --- a/drivers/counter/Makefile
> +++ b/drivers/counter/Makefile
> @@ -7,3 +7,4 @@ obj-$(CONFIG_COUNTER) += counter.o
>  obj-$(CONFIG_104_QUAD_8)	+= 104-quad-8.o
>  obj-$(CONFIG_STM32_TIMER_CNT)	+= stm32-timer-cnt.o
>  obj-$(CONFIG_STM32_LPTIMER_CNT)	+= stm32-lptimer-cnt.o
> +obj-$(CONFIG_FTM_QUADDEC)	+= ftm-quaddec.o
> diff --git a/drivers/counter/ftm-quaddec.c b/drivers/counter/ftm-quaddec.c
> new file mode 100644
> index 000000000000..1bc9e075a386
> --- /dev/null
> +++ b/drivers/counter/ftm-quaddec.c
> @@ -0,0 +1,356 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Flex Timer Module Quadrature decoder
> + *
> + * This module implements a driver for decoding the FTM quadrature
> + * of ex. a LS1021A
> + */
> +
> +#include <linux/fsl/ftm.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/of.h>
> +#include <linux/io.h>
> +#include <linux/mutex.h>
> +#include <linux/counter.h>
> +
> +struct ftm_quaddec {
> +	struct counter_device counter;
> +	struct platform_device *pdev;
> +	void __iomem *ftm_base;
> +	bool big_endian;
> +	struct mutex ftm_quaddec_mutex;
> +};
> +
> +static void ftm_read(struct ftm_quaddec *ftm, uint32_t offset, uint32_t *data)
> +{
> +	if (ftm->big_endian)
> +		*data = ioread32be(ftm->ftm_base + offset);
> +	else
> +		*data = ioread32(ftm->ftm_base + offset);
> +}
> +
> +static void ftm_write(struct ftm_quaddec *ftm, uint32_t offset, uint32_t data)
> +{
> +	if (ftm->big_endian)
> +		iowrite32be(data, ftm->ftm_base + offset);
> +	else
> +		iowrite32(data, ftm->ftm_base + offset);
> +}
> +
> +/*
> + * take mutex
> + * call ftm_clear_write_protection
> + * update settings
> + * call ftm_set_write_protection
> + * release mutex
> + */
> +static void ftm_clear_write_protection(struct ftm_quaddec *ftm)
> +{
> +	uint32_t flag;
> +
> +	/* First see if it is enabled */
> +	ftm_read(ftm, FTM_FMS, &flag);
> +
> +	if (flag & FTM_FMS_WPEN) {
> +		ftm_read(ftm, FTM_MODE, &flag);
> +		ftm_write(ftm, FTM_MODE, flag | FTM_MODE_WPDIS);
> +	}
> +}
> +
> +static void ftm_set_write_protection(struct ftm_quaddec *ftm)
> +{
> +	ftm_write(ftm, FTM_FMS, FTM_FMS_WPEN);
> +}
> +
> +static void ftm_reset_counter(struct ftm_quaddec *ftm)
> +{
> +	/* Reset hardware counter to CNTIN */
> +	ftm_write(ftm, FTM_CNT, 0x0);
> +}
> +
> +static void ftm_quaddec_init(struct ftm_quaddec *ftm)
> +{
> +	ftm_clear_write_protection(ftm);
> +
> +	/*
> +	 * Do not write in the region from the CNTIN register through the
> +	 * PWMLOAD register when FTMEN = 0.
> +	 */
> +	ftm_write(ftm, FTM_MODE, FTM_MODE_FTMEN);
> +	ftm_write(ftm, FTM_CNTIN, 0x0000);
> +	ftm_write(ftm, FTM_MOD, 0xffff);
> +	ftm_write(ftm, FTM_CNT, 0x0);
> +	ftm_write(ftm, FTM_SC, FTM_SC_PS_1);
> +
> +	/* Select quad mode */
> +	ftm_write(ftm, FTM_QDCTRL, FTM_QDCTRL_QUADEN);
> +
> +	/* Unused features and reset to default section */
> +	ftm_write(ftm, FTM_POL, 0x0);
> +	ftm_write(ftm, FTM_FLTCTRL, 0x0);
> +	ftm_write(ftm, FTM_SYNCONF, 0x0);
> +	ftm_write(ftm, FTM_SYNC, 0xffff);
> +
> +	/* Lock the FTM */
> +	ftm_set_write_protection(ftm);
> +}
> +
> +static void ftm_quaddec_disable(struct ftm_quaddec *ftm)
> +{
> +	ftm_write(ftm, FTM_MODE, 0);
> +}
> +
> +static int ftm_quaddec_get_prescaler(struct counter_device *counter,
> +				     struct counter_count *count,
> +				     size_t *cnt_mode)
> +{
> +	struct ftm_quaddec *ftm = counter->priv;
> +	uint32_t scflags;
> +
> +	ftm_read(ftm, FTM_SC, &scflags);
> +
> +	*cnt_mode = scflags & FTM_SC_PS_MASK;

FIELD_GET and FIELD_PREP are a tidy way of doing these sorts of
accesses. Helpfully they also save a reviewer having to sanity
check that the offset is 0 as it is here.


> +
> +	return 0;
> +}
> +
> +static int ftm_quaddec_set_prescaler(struct counter_device *counter,
> +				     struct counter_count *count,
> +				     size_t cnt_mode)
> +{
> +	struct ftm_quaddec *ftm = counter->priv;
> +
> +	uint32_t scflags;
> +
> +	mutex_lock(&ftm->ftm_quaddec_mutex);
> +
> +	ftm_read(ftm, FTM_SC, &scflags);
> +
> +	scflags &= ~FTM_SC_PS_MASK;
> +	cnt_mode &= FTM_SC_PS_MASK; /*just to be 100% sure*/

nitpick: Comment syntax is /* just to be 100% sure */

> +
> +	scflags |= cnt_mode;
> +
> +	/* Write */
> +	ftm_clear_write_protection(ftm);
> +	ftm_write(ftm, FTM_SC, scflags);
> +	ftm_set_write_protection(ftm);
> +
> +	/* Also resets the counter as it is undefined anyway now */
> +	ftm_reset_counter(ftm);
> +
> +	mutex_unlock(&ftm->ftm_quaddec_mutex);
> +	return 0;
> +}
> +
> +static const char * const ftm_quaddec_prescaler[] = {
> +	"1", "2", "4", "8", "16", "32", "64", "128"
> +};
> +
> +static struct counter_count_enum_ext ftm_quaddec_prescaler_enum = {
> +	.items = ftm_quaddec_prescaler,
> +	.num_items = ARRAY_SIZE(ftm_quaddec_prescaler),
> +	.get = ftm_quaddec_get_prescaler,
> +	.set = ftm_quaddec_set_prescaler
> +};
> +
> +enum ftm_quaddec_synapse_action {
> +	FTM_QUADDEC_SYNAPSE_ACTION_BOTH_EDGES,
> +};
> +
> +static enum counter_synapse_action ftm_quaddec_synapse_actions[] = {
> +	[FTM_QUADDEC_SYNAPSE_ACTION_BOTH_EDGES] =
> +	COUNTER_SYNAPSE_ACTION_BOTH_EDGES
> +};
> +
> +enum ftm_quaddec_count_function {
> +	FTM_QUADDEC_COUNT_ENCODER_MODE_1,
> +};
> +
> +static const enum counter_count_function ftm_quaddec_count_functions[] = {
> +	[FTM_QUADDEC_COUNT_ENCODER_MODE_1] =
> +	COUNTER_COUNT_FUNCTION_QUADRATURE_X4
> +};
> +
> +static int ftm_quaddec_count_read(struct counter_device *counter,
> +				  struct counter_count *count,
> +				  struct counter_count_read_value *val)
> +{
> +	struct ftm_quaddec *const ftm = counter->priv;
> +	uint32_t cntval;
> +
> +	ftm_read(ftm, FTM_CNT, &cntval);
> +
> +	counter_count_read_value_set(val, COUNTER_COUNT_POSITION, &cntval);
> +
> +	return 0;
> +}
> +
> +static int ftm_quaddec_count_write(struct counter_device *counter,
> +				   struct counter_count *count,
> +				   struct counter_count_write_value *val)
> +{
> +	struct ftm_quaddec *const ftm = counter->priv;
> +	u32 cnt;
> +	int err;
> +
> +	err = counter_count_write_value_get(&cnt, COUNTER_COUNT_POSITION, val);
> +	if (err)
> +		return err;
> +
> +	if (cnt != 0) {
> +		dev_warn(&ftm->pdev->dev, "Can only accept '0' as new counter value\n");
> +		return -EINVAL;
> +	}
> +
> +	ftm_reset_counter(ftm);
> +
> +	return 0;
> +}
> +
> +static int ftm_quaddec_count_function_get(struct counter_device *counter,
> +					  struct counter_count *count,
> +					  size_t *function)
> +{
> +	*function = FTM_QUADDEC_COUNT_ENCODER_MODE_1;
> +
> +	return 0;
> +}
> +
> +static int ftm_quaddec_action_get(struct counter_device *counter,
> +				  struct counter_count *count,
> +				  struct counter_synapse *synapse,
> +				  size_t *action)
> +{
> +	*action = FTM_QUADDEC_SYNAPSE_ACTION_BOTH_EDGES;
> +
> +	return 0;
> +}
> +
> +static const struct counter_ops ftm_quaddec_cnt_ops = {
> +	.count_read = ftm_quaddec_count_read,
> +	.count_write = ftm_quaddec_count_write,
> +	.function_get = ftm_quaddec_count_function_get,
> +	.action_get = ftm_quaddec_action_get,
> +};
> +
> +static struct counter_signal ftm_quaddec_signals[] = {
> +	{
> +		.id = 0,
> +		.name = "Channel 1 Quadrature A"
> +	},
> +	{
> +		.id = 1,
> +		.name = "Channel 1 Quadrature B"
> +	}
> +};
> +
> +static struct counter_synapse ftm_quaddec_count_synapses[] = {
> +	{
> +		.actions_list = ftm_quaddec_synapse_actions,
> +		.num_actions = ARRAY_SIZE(ftm_quaddec_synapse_actions),
> +		.signal = &ftm_quaddec_signals[0]
> +	},
> +	{
> +		.actions_list = ftm_quaddec_synapse_actions,
> +		.num_actions = ARRAY_SIZE(ftm_quaddec_synapse_actions),
> +		.signal = &ftm_quaddec_signals[1]
> +	}
> +};
> +
> +static const struct counter_count_ext ftm_quaddec_count_ext[] = {
> +	COUNTER_COUNT_ENUM("prescaler", &ftm_quaddec_prescaler_enum),
> +	COUNTER_COUNT_ENUM_AVAILABLE("prescaler", &ftm_quaddec_prescaler_enum),
> +};
> +
> +static struct counter_count ftm_quaddec_counts = {
> +	.id = 0,
> +	.name = "Channel 1 Count",
> +	.functions_list = ftm_quaddec_count_functions,
> +	.num_functions = ARRAY_SIZE(ftm_quaddec_count_functions),
> +	.synapses = ftm_quaddec_count_synapses,
> +	.num_synapses = ARRAY_SIZE(ftm_quaddec_count_synapses),
> +	.ext = ftm_quaddec_count_ext,
> +	.num_ext = ARRAY_SIZE(ftm_quaddec_count_ext)
> +};
> +
> +static int ftm_quaddec_probe(struct platform_device *pdev)
> +{
> +	struct ftm_quaddec *ftm;
> +
> +	struct device_node *node = pdev->dev.of_node;
> +	struct resource *io;
> +	int ret;
> +
> +	ftm = devm_kzalloc(&pdev->dev, sizeof(*ftm), GFP_KERNEL);
> +	if (!ftm)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, ftm);
> +
> +	io = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!io) {
> +		dev_err(&pdev->dev, "Failed to get memory region\n");
> +		return -ENODEV;
> +	}
> +
> +	ftm->pdev = pdev;
> +	ftm->big_endian = of_property_read_bool(node, "big-endian");
> +	ftm->ftm_base = devm_ioremap(&pdev->dev, io->start, resource_size(io));
> +
> +	if (!ftm->ftm_base) {
> +		dev_err(&pdev->dev, "Failed to map memory region\n");
> +		return -EINVAL;
> +	}
> +	ftm->counter.name = dev_name(&pdev->dev);
> +	ftm->counter.parent = &pdev->dev;
> +	ftm->counter.ops = &ftm_quaddec_cnt_ops;
> +	ftm->counter.counts = &ftm_quaddec_counts;
> +	ftm->counter.num_counts = 1;
> +	ftm->counter.signals = ftm_quaddec_signals;
> +	ftm->counter.num_signals = ARRAY_SIZE(ftm_quaddec_signals);
> +	ftm->counter.priv = ftm;
> +
> +	mutex_init(&ftm->ftm_quaddec_mutex);
> +
> +	ftm_quaddec_init(ftm);
> +
> +	ret = counter_register(&ftm->counter);
> +	if (ret)
> +		ftm_quaddec_disable(ftm);
> +
> +	return ret;
> +}
> +
> +static int ftm_quaddec_remove(struct platform_device *pdev)
> +{
> +	struct ftm_quaddec *ftm = platform_get_drvdata(pdev);
> +
> +	counter_unregister(&ftm->counter);
> +
> +	ftm_quaddec_disable(ftm);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id ftm_quaddec_match[] = {
> +	{ .compatible = "fsl,ftm-quaddec" },
> +	{},
> +};
> +
> +static struct platform_driver ftm_quaddec_driver = {
> +	.driver = {
> +		.name = "ftm-quaddec",
> +		.owner = THIS_MODULE,
No need to set this, the call to __platform_driver_register
that comes from the module_platform_driver macro below
will deal with this for you.

> +		.of_match_table = ftm_quaddec_match,
> +	},
> +	.probe = ftm_quaddec_probe,
> +	.remove = ftm_quaddec_remove,
> +};
> +
> +module_platform_driver(ftm_quaddec_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Kjeld Flarup <kfa@deif.com");
> +MODULE_AUTHOR("Patrick Havelange <patrick.havelange@essensium.com");

[PATCH v2 6/7] counter: ftm-quaddec: Documentation: Add specific counter sysfs documentation

[Patrick Havelange]

This adds documentation for the specific prescaler entry.

Signed-off-by: Patrick Havelange <patrick.havelange@essensium.com>
---
Changes v2
 - Add doc for prescaler entry
---
 .../ABI/testing/sysfs-bus-counter-ftm-quaddec    | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-counter-ftm-quaddec

diff --git a/Documentation/ABI/testing/sysfs-bus-counter-ftm-quaddec b/Documentation/ABI/testing/sysfs-bus-counter-ftm-quaddec
new file mode 100644
index 000000000000..2da629d6d485
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-counter-ftm-quaddec
@@ -0,0 +1,16 @@
+What:		/sys/bus/counter/devices/counterX/countY/prescaler_available
+KernelVersion:	5.1
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Discrete set of available values for the respective Count Y
+		configuration are listed in this file. Values are delimited by
+		newline characters.
+
+What:		/sys/bus/counter/devices/counterX/countY/prescaler
+KernelVersion:	5.1
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Configure the prescaler value associated with Count Y.
+		On the FlexTimer, the counter clock source passes through a
+		prescaler that is a 7-bit counter. This acts like a clock
+		divider.
-- 
2.19.1

Re: [PATCH v2 6/7] counter: ftm-quaddec: Documentation: Add specific counter sysfs documentation

[William Breathitt Gray]

On Wed, Mar 06, 2019 at 12:12:07PM +0100, Patrick Havelange wrote:
> This adds documentation for the specific prescaler entry.
> 
> Signed-off-by: Patrick Havelange <patrick.havelange@essensium.com>
> ---
> Changes v2
>  - Add doc for prescaler entry
> ---
>  .../ABI/testing/sysfs-bus-counter-ftm-quaddec    | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-bus-counter-ftm-quaddec
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-counter-ftm-quaddec b/Documentation/ABI/testing/sysfs-bus-counter-ftm-quaddec
> new file mode 100644
> index 000000000000..2da629d6d485
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-bus-counter-ftm-quaddec
> @@ -0,0 +1,16 @@
> +What:		/sys/bus/counter/devices/counterX/countY/prescaler_available
> +KernelVersion:	5.1
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		Discrete set of available values for the respective Count Y
> +		configuration are listed in this file. Values are delimited by
> +		newline characters.
> +
> +What:		/sys/bus/counter/devices/counterX/countY/prescaler
> +KernelVersion:	5.1
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		Configure the prescaler value associated with Count Y.
> +		On the FlexTimer, the counter clock source passes through a
> +		prescaler that is a 7-bit counter. This acts like a clock
> +		divider.
> -- 
> 2.19.1

Hmm, prescalers seem common enough among counter devices to permit these
attributes to be listed in the sysfs-bus-counter documentation file.
However, I'd like to wait until we get another counter driver for a
device with a prescaler before we make that move. From there, we'll have
a better vantage point to determine a fitting standard prescaler
attribute behavior.

So for now, we'll keep these attributes documented here in the
sysfs-bus-counter-ftm-quaddec file, until the time comes to broach the
discussion again.

William Breathitt Gray

Re: [PATCH v2 6/7] counter: ftm-quaddec: Documentation: Add specific counter sysfs documentation

[Jonathan Cameron]

On Thu, 7 Mar 2019 20:42:16 +0900
William Breathitt Gray <vilhelm.gray@gmail.com> wrote:

> On Wed, Mar 06, 2019 at 12:12:07PM +0100, Patrick Havelange wrote:
> > This adds documentation for the specific prescaler entry.
> > 
> > Signed-off-by: Patrick Havelange <patrick.havelange@essensium.com>
> > ---
> > Changes v2
> >  - Add doc for prescaler entry
> > ---
> >  .../ABI/testing/sysfs-bus-counter-ftm-quaddec    | 16 ++++++++++++++++
> >  1 file changed, 16 insertions(+)
> >  create mode 100644 Documentation/ABI/testing/sysfs-bus-counter-ftm-quaddec
> > 
> > diff --git a/Documentation/ABI/testing/sysfs-bus-counter-ftm-quaddec b/Documentation/ABI/testing/sysfs-bus-counter-ftm-quaddec
> > new file mode 100644
> > index 000000000000..2da629d6d485
> > --- /dev/null
> > +++ b/Documentation/ABI/testing/sysfs-bus-counter-ftm-quaddec
> > @@ -0,0 +1,16 @@
> > +What:		/sys/bus/counter/devices/counterX/countY/prescaler_available
> > +KernelVersion:	5.1
> > +Contact:	linux-iio@vger.kernel.org
> > +Description:
> > +		Discrete set of available values for the respective Count Y
> > +		configuration are listed in this file. Values are delimited by
> > +		newline characters.
> > +
> > +What:		/sys/bus/counter/devices/counterX/countY/prescaler
> > +KernelVersion:	5.1
> > +Contact:	linux-iio@vger.kernel.org
> > +Description:
> > +		Configure the prescaler value associated with Count Y.
> > +		On the FlexTimer, the counter clock source passes through a
> > +		prescaler that is a 7-bit counter. This acts like a clock
> > +		divider.
> > -- 
> > 2.19.1  
> 
> Hmm, prescalers seem common enough among counter devices to permit these
> attributes to be listed in the sysfs-bus-counter documentation file.
> However, I'd like to wait until we get another counter driver for a
> device with a prescaler before we make that move. From there, we'll have
> a better vantage point to determine a fitting standard prescaler
> attribute behavior.
> 
> So for now, we'll keep these attributes documented here in the
> sysfs-bus-counter-ftm-quaddec file, until the time comes to broach the
> discussion again.
Agreed. As long as the definition is sufficiently non-specific so it can be
moved later.  I'm not sure for example that the docs need to say that it is
a 7 bit counter. That should be apparent from prescaler_available - or at
least possible values should be which is all we need to know.

Jonathan
> 
> William Breathitt Gray

[PATCH v2 7/7] LS1021A: dtsi: add ftm quad decoder entries

[Patrick Havelange]

Add the 4 Quadrature counters for this board.

Signed-off-by: Patrick Havelange <patrick.havelange@essensium.com>
Reviewed-by: Esben Haabendal <esben@haabendal.dk>
---
Changes v2
 - None
---
 arch/arm/boot/dts/ls1021a.dtsi | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/arch/arm/boot/dts/ls1021a.dtsi b/arch/arm/boot/dts/ls1021a.dtsi
index ed0941292172..0168fb62590a 100644
--- a/arch/arm/boot/dts/ls1021a.dtsi
+++ b/arch/arm/boot/dts/ls1021a.dtsi
@@ -433,6 +433,34 @@
 			status = "disabled";
 		};
 
+		counter0: counter@29d0000 {
+			compatible = "fsl,ftm-quaddec";
+			reg = <0x0 0x29d0000 0x0 0x10000>;
+			big-endian;
+			status = "disabled";
+		};
+
+		counter1: counter@29e0000 {
+			compatible = "fsl,ftm-quaddec";
+			reg = <0x0 0x29e0000 0x0 0x10000>;
+			big-endian;
+			status = "disabled";
+		};
+
+		counter2: counter@29f0000 {
+			compatible = "fsl,ftm-quaddec";
+			reg = <0x0 0x29f0000 0x0 0x10000>;
+			big-endian;
+			status = "disabled";
+		};
+
+		counter3: counter@2a00000 {
+			compatible = "fsl,ftm-quaddec";
+			reg = <0x0 0x2a00000 0x0 0x10000>;
+			big-endian;
+			status = "disabled";
+		};
+
 		gpio0: gpio@2300000 {
 			compatible = "fsl,ls1021a-gpio", "fsl,qoriq-gpio";
 			reg = <0x0 0x2300000 0x0 0x10000>;
-- 
2.19.1

Re: [PATCH v2 0/7] FlexTimer Module Quadrature decoder counter

[William Breathitt Gray]

On Wed, Mar 06, 2019 at 12:12:01PM +0100, Patrick Havelange wrote:
> This patch serie is to be applied on top of 
> https://patchwork.kernel.org/project/linux-iio/list/?series=147
> (a more recent version of the serie is available here : 
> https://gitlab.com/vilhelmgray/iio/tree/generic_counter_v10 )
> 
> Main changes in v2: 
> The code is a bit simpler, thanks to more use of devm_* functions.
> The polling/32bit signed version has been dropped, as not needed and
> no other driver is doing that.
> 
> 
> Patrick Havelange (7):
>   include/fsl: add common FlexTimer #defines in a separate header.
>   drivers/pwm: pwm-fsl-ftm: use common header for FlexTimer #defines
>   drivers/clocksource: timer-fsl-ftm: use common header for FlexTimer
>     #defines
>   dt-bindings: counter: ftm-quaddec
>   counter: add FlexTimer Module Quadrature decoder counter driver
>   counter: ftm-quaddec: Documentation: Add specific counter sysfs
>     documentation
>   LS1021A: dtsi: add ftm quad decoder entries
> 
>  .../ABI/testing/sysfs-bus-counter-ftm-quaddec |  16 +
>  .../bindings/counter/ftm-quaddec.txt          |  18 +
>  arch/arm/boot/dts/ls1021a.dtsi                |  28 ++
>  drivers/clocksource/timer-fsl-ftm.c           |  15 +-
>  drivers/counter/Kconfig                       |   9 +
>  drivers/counter/Makefile                      |   1 +
>  drivers/counter/ftm-quaddec.c                 | 356 ++++++++++++++++++
>  drivers/pwm/pwm-fsl-ftm.c                     |  44 +--
>  include/linux/fsl/ftm.h                       |  88 +++++
>  9 files changed, 519 insertions(+), 56 deletions(-)
>  create mode 100644 Documentation/ABI/testing/sysfs-bus-counter-ftm-quaddec
>  create mode 100644 Documentation/devicetree/bindings/counter/ftm-quaddec.txt
>  create mode 100644 drivers/counter/ftm-quaddec.c
>  create mode 100644 include/linux/fsl/ftm.h
> 
> -- 
> 2.19.1

Patrick,

I see you dropped the polling support in this version. If the need
arises in the future, we can discuss a possible ways of resolving your
latency issues; I imagine interrupts during overflow/underflow events to
be a common behavior among counter devices so those too may result in
latency issues as you discovered in your case.

Jonathan,

If you are satisfied with the changes in this patchset, let me know
which patches you like and I'll add respective Reviewed-by tags for you
for the next Counter subsystem introduction patchset submission.

William Breathitt Gray