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, 26 insertions, 36 deletions

diff --git a/drivers/counter/interrupt-cnt.c b/drivers/counter/interrupt-cnt.c
index 1de4243db488..8514a87fcbee 100644
--- a/drivers/counter/interrupt-cnt.c
+++ b/drivers/counter/interrupt-cnt.c
@@ -10,6 +10,7 @@
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
+#include <linux/types.h>
 
 #define INTERRUPT_CNT_NAME "interrupt-cnt"
 
@@ -33,30 +34,23 @@ static irqreturn_t interrupt_cnt_isr(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
-static ssize_t interrupt_cnt_enable_read(struct counter_device *counter,
-					 struct counter_count *count,
-					 void *private, char *buf)
+static int interrupt_cnt_enable_read(struct counter_device *counter,
+				     struct counter_count *count, u8 *enable)
 {
 	struct interrupt_cnt_priv *priv = counter->priv;
 
-	return sysfs_emit(buf, "%d\n", priv->enabled);
+	*enable = priv->enabled;
+
+	return 0;
 }
 
-static ssize_t interrupt_cnt_enable_write(struct counter_device *counter,
-					  struct counter_count *count,
-					  void *private, const char *buf,
-					  size_t len)
+static int interrupt_cnt_enable_write(struct counter_device *counter,
+				      struct counter_count *count, u8 enable)
 {
 	struct interrupt_cnt_priv *priv = counter->priv;
-	bool enable;
-	ssize_t ret;
-
-	ret = kstrtobool(buf, &enable);
-	if (ret)
-		return ret;
 
 	if (priv->enabled == enable)
-		return len;
+		return 0;
 
 	if (enable) {
 		priv->enabled = true;
@@ -66,33 +60,30 @@ static ssize_t interrupt_cnt_enable_write(struct counter_device *counter,
 		priv->enabled = false;
 	}
 
-	return len;
+	return 0;
 }
 
-static const struct counter_count_ext interrupt_cnt_ext[] = {
-	{
-		.name = "enable",
-		.read = interrupt_cnt_enable_read,
-		.write = interrupt_cnt_enable_write,
-	},
+static struct counter_comp interrupt_cnt_ext[] = {
+	COUNTER_COMP_ENABLE(interrupt_cnt_enable_read,
+			    interrupt_cnt_enable_write),
 };
 
 static const enum counter_synapse_action interrupt_cnt_synapse_actions[] = {
 	COUNTER_SYNAPSE_ACTION_RISING_EDGE,
 };
 
-static int interrupt_cnt_action_get(struct counter_device *counter,
-				    struct counter_count *count,
-				    struct counter_synapse *synapse,
-				    size_t *action)
+static int interrupt_cnt_action_read(struct counter_device *counter,
+				     struct counter_count *count,
+				     struct counter_synapse *synapse,
+				     enum counter_synapse_action *action)
 {
-	*action = 0;
+	*action = COUNTER_SYNAPSE_ACTION_RISING_EDGE;
 
 	return 0;
 }
 
 static int interrupt_cnt_read(struct counter_device *counter,
-			      struct counter_count *count, unsigned long *val)
+			      struct counter_count *count, u64 *val)
 {
 	struct interrupt_cnt_priv *priv = counter->priv;
 
@@ -102,8 +93,7 @@ static int interrupt_cnt_read(struct counter_device *counter,
 }
 
 static int interrupt_cnt_write(struct counter_device *counter,
-			       struct counter_count *count,
-			       const unsigned long val)
+			       struct counter_count *count, const u64 val)
 {
 	struct interrupt_cnt_priv *priv = counter->priv;
 
@@ -119,11 +109,11 @@ static const enum counter_function interrupt_cnt_functions[] = {
 	COUNTER_FUNCTION_INCREASE,
 };
 
-static int interrupt_cnt_function_get(struct counter_device *counter,
-				      struct counter_count *count,
-				      size_t *function)
+static int interrupt_cnt_function_read(struct counter_device *counter,
+				       struct counter_count *count,
+				       enum counter_function *function)
 {
-	*function = 0;
+	*function = COUNTER_FUNCTION_INCREASE;
 
 	return 0;
 }
@@ -148,10 +138,10 @@ static int interrupt_cnt_signal_read(struct counter_device *counter,
 }
 
 static const struct counter_ops interrupt_cnt_ops = {
-	.action_get = interrupt_cnt_action_get,
+	.action_read = interrupt_cnt_action_read,
 	.count_read = interrupt_cnt_read,
 	.count_write = interrupt_cnt_write,
-	.function_get = interrupt_cnt_function_get,
+	.function_read = interrupt_cnt_function_read,
 	.signal_read  = interrupt_cnt_signal_read,
 };