counter: Internalize sysfs interface code

This is a reimplementation of the Generic Counter driver interface.
There are no modifications to the Counter subsystem userspace interface,
so existing userspace applications should continue to run seamlessly.

The purpose of this patch is to internalize the sysfs interface code
among the various counter drivers into a shared module. Counter drivers
pass and take data natively (i.e. u8, u64, etc.) and the shared counter
module handles the translation between the sysfs interface and the
device drivers. This guarantees a standard userspace interface for all
counter drivers, and helps generalize the Generic Counter driver ABI in
order to support the Generic Counter chrdev interface (introduced in a
subsequent patch) without significant changes to the existing counter
drivers.

Note, Counter device registration is the same as before: drivers
populate a struct counter_device with components and callbacks, then
pass the structure to the devm_counter_register function. However,
what's different now is how the Counter subsystem code handles this
registration internally.

Whereas before callbacks would interact directly with sysfs data, this
interaction is now abstracted and instead callbacks interact with native
C data types. The counter_comp structure forms the basis for Counter
extensions.

The counter-sysfs.c file contains the code to parse through the
counter_device structure and register the requested components and
extensions. Attributes are created and populated based on type, with
respective translation functions to handle the mapping between sysfs and
the counter driver callbacks.

The translation performed for each attribute is straightforward: the
attribute type and data is parsed from the counter_attribute structure,
the respective counter driver read/write callback is called, and sysfs
I/O is handled before or after the driver read/write function is called.

Cc: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Cc: Patrick Havelange <patrick.havelange@essensium.com>
Cc: Kamel Bouhara <kamel.bouhara@bootlin.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Alexandre Torgue <alexandre.torgue@st.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Syed Nayyar Waris <syednwaris@gmail.com>
Reviewed-by: David Lechner <david@lechnology.com>
Tested-by: David Lechner <david@lechnology.com>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com> # for stm32
Link: https://lore.kernel.org/r/c68b4a1ffb195c1a2f65e8dd5ad7b7c14e79c6ef.1630031207.git.vilhelm.gray@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

1 files changed, 23 insertions, 37 deletions

diff --git a/drivers/counter/ftm-quaddec.c b/drivers/counter/ftm-quaddec.c
index 53c15f84909b..5ef0478709cd 100644
--- a/drivers/counter/ftm-quaddec.c
+++ b/drivers/counter/ftm-quaddec.c
@@ -14,6 +14,7 @@
 #include <linux/mutex.h>
 #include <linux/counter.h>
 #include <linux/bitfield.h>
+#include <linux/types.h>
 
 #define FTM_FIELD_UPDATE(ftm, offset, mask, val)			\
 	({								\
@@ -115,8 +116,7 @@ static void ftm_quaddec_disable(void *ftm)
 }
 
 static int ftm_quaddec_get_prescaler(struct counter_device *counter,
-				     struct counter_count *count,
-				     size_t *cnt_mode)
+				     struct counter_count *count, u32 *cnt_mode)
 {
 	struct ftm_quaddec *ftm = counter->priv;
 	uint32_t scflags;
@@ -129,8 +129,7 @@ static int ftm_quaddec_get_prescaler(struct counter_device *counter,
 }
 
 static int ftm_quaddec_set_prescaler(struct counter_device *counter,
-				     struct counter_count *count,
-				     size_t cnt_mode)
+				     struct counter_count *count, u32 cnt_mode)
 {
 	struct ftm_quaddec *ftm = counter->priv;
 
@@ -151,33 +150,17 @@ 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 const 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_function ftm_quaddec_count_functions[] = {
-	[FTM_QUADDEC_COUNT_ENCODER_MODE_1] = COUNTER_FUNCTION_QUADRATURE_X4
+	COUNTER_FUNCTION_QUADRATURE_X4
 };
 
 static int ftm_quaddec_count_read(struct counter_device *counter,
 				  struct counter_count *count,
-				  unsigned long *val)
+				  u64 *val)
 {
 	struct ftm_quaddec *const ftm = counter->priv;
 	uint32_t cntval;
@@ -191,7 +174,7 @@ static int ftm_quaddec_count_read(struct counter_device *counter,
 
 static int ftm_quaddec_count_write(struct counter_device *counter,
 				   struct counter_count *count,
-				   const unsigned long val)
+				   const u64 val)
 {
 	struct ftm_quaddec *const ftm = counter->priv;
 
@@ -205,21 +188,21 @@ static int ftm_quaddec_count_write(struct counter_device *counter,
 	return 0;
 }
 
-static int ftm_quaddec_count_function_get(struct counter_device *counter,
-					  struct counter_count *count,
-					  size_t *function)
+static int ftm_quaddec_count_function_read(struct counter_device *counter,
+					   struct counter_count *count,
+					   enum counter_function *function)
 {
-	*function = FTM_QUADDEC_COUNT_ENCODER_MODE_1;
+	*function = COUNTER_FUNCTION_QUADRATURE_X4;
 
 	return 0;
 }
 
-static int ftm_quaddec_action_get(struct counter_device *counter,
-				  struct counter_count *count,
-				  struct counter_synapse *synapse,
-				  size_t *action)
+static int ftm_quaddec_action_read(struct counter_device *counter,
+				   struct counter_count *count,
+				   struct counter_synapse *synapse,
+				   enum counter_synapse_action *action)
 {
-	*action = FTM_QUADDEC_SYNAPSE_ACTION_BOTH_EDGES;
+	*action = COUNTER_SYNAPSE_ACTION_BOTH_EDGES;
 
 	return 0;
 }
@@ -227,8 +210,8 @@ static int ftm_quaddec_action_get(struct counter_device *counter,
 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,
+	.function_read = ftm_quaddec_count_function_read,
+	.action_read = ftm_quaddec_action_read,
 };
 
 static struct counter_signal ftm_quaddec_signals[] = {
@@ -255,9 +238,12 @@ static struct counter_synapse ftm_quaddec_count_synapses[] = {
 	}
 };
 
-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 DEFINE_COUNTER_ENUM(ftm_quaddec_prescaler_enum, ftm_quaddec_prescaler);
+
+static struct counter_comp ftm_quaddec_count_ext[] = {
+	COUNTER_COMP_COUNT_ENUM("prescaler", ftm_quaddec_get_prescaler,
+				ftm_quaddec_set_prescaler,
+				ftm_quaddec_prescaler_enum),
 };
 
 static struct counter_count ftm_quaddec_counts = {