Commit a3b9a999 authored by Patrick Havelange's avatar Patrick Havelange Committed by Greg Kroah-Hartman
Browse files

counter: add FlexTimer Module Quadrature decoder counter driver 



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

Signed-off-by: default avatarPatrick Havelange <patrick.havelange@essensium.com>
Signed-off-by: default avatarWilliam Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7f2e3ea3

drivers/counter/Kconfig

+9 −0
Original line number Diff line number Diff line
@@ -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

drivers/counter/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -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

drivers/counter/ftm-quaddec.c

0 → 100644
+356 −0
Original line number Diff line number Diff line 
// 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>

#include <linux/bitfield.h>



#define FTM_FIELD_UPDATE(ftm, offset, mask, val)			\

	({								\

		uint32_t flags;						\

		ftm_read(ftm, offset, &flags);				\

		flags &= ~mask;						\

		flags |= FIELD_PREP(mask, val);				\

		ftm_write(ftm, offset, flags);				\

	})



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);

}



/* 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_FIELD_UPDATE(ftm, FTM_MODE, FTM_MODE_WPDIS, 1);

}



static void ftm_set_write_protection(struct ftm_quaddec *ftm)

{

	FTM_FIELD_UPDATE(ftm, FTM_FMS, FTM_FMS_WPEN, 1);

}



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.

	 * Also reset other fields to zero

	 */

	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);

	/* Set prescaler, reset other fields to zero */

	ftm_write(ftm, FTM_SC, FTM_SC_PS_1);



	/* Select quad mode, reset other fields to zero */

	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_clear_write_protection(ftm);

	ftm_write(ftm, FTM_MODE, 0);

	ftm_write(ftm, FTM_QDCTRL, 0);

	/*

	 * This is enough to disable the counter. No clock has been

	 * selected by writing to FTM_SC in init()

	 */

	ftm_set_write_protection(ftm);

}



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 = FIELD_GET(FTM_SC_PS_MASK, scflags);



	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;



	mutex_lock(&ftm->ftm_quaddec_mutex);



	ftm_clear_write_protection(ftm);

	FTM_FIELD_UPDATE(ftm, FTM_SC, FTM_SC_PS_MASK, cnt_mode);

	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 Phase A"

	},

	{

		.id = 1,

		.name = "Channel 1 Phase 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",

		.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");