drivers/mfd/ocelot-spi.c - linux - Git at Google

 // SPDX-License-Identifier: (GPL-2.0 OR MIT)
 /*
  * SPI core driver for the Ocelot chip family.
  *
  * This driver will handle everything necessary to allow for communication over
  * SPI to the VSC7511, VSC7512, VSC7513 and VSC7514 chips. The main functions
  * are to prepare the chip's SPI interface for a specific bus speed, and a host
  * processor's endianness. This will create and distribute regmaps for any
  * children.
  *
  * Copyright 2021-2022 Innovative Advantage Inc.
  *
  * Author: Colin Foster <colin.foster@in-advantage.com>
  */

 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/export.h>
 #include <linux/ioport.h>
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
 #include <linux/regmap.h>
 #include <linux/spi/spi.h>
 #include <linux/types.h>
 #include <linux/units.h>

 #include "ocelot.h"

 #define REG_DEV_CPUORG_IF_CTRL		0x0000
 #define REG_DEV_CPUORG_IF_CFGSTAT	0x0004

 #define CFGSTAT_IF_NUM_VCORE		(0 << 24)
 #define CFGSTAT_IF_NUM_VRAP		(1 << 24)
 #define CFGSTAT_IF_NUM_SI		(2 << 24)
 #define CFGSTAT_IF_NUM_MIIM		(3 << 24)

 #define VSC7512_DEVCPU_ORG_RES_START	0x71000000
 #define VSC7512_DEVCPU_ORG_RES_SIZE	0x38

 #define VSC7512_CHIP_REGS_RES_START	0x71070000
 #define VSC7512_CHIP_REGS_RES_SIZE	0x14

 static const struct resource vsc7512_dev_cpuorg_resource =
 	DEFINE_RES_REG_NAMED(VSC7512_DEVCPU_ORG_RES_START,
 			     VSC7512_DEVCPU_ORG_RES_SIZE,
 			     "devcpu_org");

 static const struct resource vsc7512_gcb_resource =
 	DEFINE_RES_REG_NAMED(VSC7512_CHIP_REGS_RES_START,
 			     VSC7512_CHIP_REGS_RES_SIZE,
 			     "devcpu_gcb_chip_regs");

 static int ocelot_spi_initialize(struct device *dev)
 {
 	struct ocelot_ddata *ddata = dev_get_drvdata(dev);
 	u32 val, check;
 	int err;

 	val = OCELOT_SPI_BYTE_ORDER;

 	/*
 	 * The SPI address must be big-endian, but we want the payload to match
 	 * our CPU. These are two bits (0 and 1) but they're repeated such that
 	 * the write from any configuration will be valid. The four
 	 * configurations are:
 	 *
 	 * 0b00: little-endian, MSB first
 	 * |            111111   | 22221111 | 33222222 |
 	 * | 76543210 | 54321098 | 32109876 | 10987654 |
 	 *
 	 * 0b01: big-endian, MSB first
 	 * | 33222222 | 22221111 | 111111   |          |
 	 * | 10987654 | 32109876 | 54321098 | 76543210 |
 	 *
 	 * 0b10: little-endian, LSB first
 	 * |              111111 | 11112222 | 22222233 |
 	 * | 01234567 | 89012345 | 67890123 | 45678901 |
 	 *
 	 * 0b11: big-endian, LSB first
 	 * | 22222233 | 11112222 |   111111 |          |
 	 * | 45678901 | 67890123 | 89012345 | 01234567 |
 	 */
 	err = regmap_write(ddata->cpuorg_regmap, REG_DEV_CPUORG_IF_CTRL, val);
 	if (err)
 		return err;

 	/*
 	 * Apply the number of padding bytes between a read request and the data
 	 * payload. Some registers have access times of up to 1us, so if the
 	 * first payload bit is shifted out too quickly, the read will fail.
 	 */
 	val = ddata->spi_padding_bytes;
 	err = regmap_write(ddata->cpuorg_regmap, REG_DEV_CPUORG_IF_CFGSTAT, val);
 	if (err)
 		return err;

 	/*
 	 * After we write the interface configuration, read it back here. This
 	 * will verify several different things. The first is that the number of
 	 * padding bytes actually got written correctly. These are found in bits
 	 * 0:3.
 	 *
 	 * The second is that bit 16 is cleared. Bit 16 is IF_CFGSTAT:IF_STAT,
 	 * and will be set if the register access is too fast. This would be in
 	 * the condition that the number of padding bytes is insufficient for
 	 * the SPI bus frequency.
 	 *
 	 * The last check is for bits 31:24, which define the interface by which
 	 * the registers are being accessed. Since we're accessing them via the
 	 * serial interface, it must return IF_NUM_SI.
 	 */
 	check = val | CFGSTAT_IF_NUM_SI;

 	err = regmap_read(ddata->cpuorg_regmap, REG_DEV_CPUORG_IF_CFGSTAT, &val);
 	if (err)
 		return err;

 	if (check != val)
 		return -ENODEV;

 	return 0;
 }

 static const struct regmap_config ocelot_spi_regmap_config = {
 	.reg_bits = 24,
 	.reg_stride = 4,
 	.reg_shift = REGMAP_DOWNSHIFT(2),
 	.val_bits = 32,

 	.write_flag_mask = 0x80,

 	.use_single_read = true,
 	.use_single_write = true,
 	.can_multi_write = false,

 	.reg_format_endian = REGMAP_ENDIAN_BIG,
 	.val_format_endian = REGMAP_ENDIAN_NATIVE,
 };

 static int ocelot_spi_regmap_bus_read(void *context, const void *reg, size_t reg_size,
 				      void *val, size_t val_size)
 {
 	struct spi_transfer xfers[3] = {0};
 	struct device *dev = context;
 	struct ocelot_ddata *ddata;
 	struct spi_device *spi;
 	unsigned int index = 0;

 	ddata = dev_get_drvdata(dev);
 	spi = to_spi_device(dev);

 	xfers[index].tx_buf = reg;
 	xfers[index].len = reg_size;
 	index++;

 	if (ddata->spi_padding_bytes) {
 		xfers[index].len = ddata->spi_padding_bytes;
 		xfers[index].tx_buf = ddata->dummy_buf;
 		xfers[index].dummy_data = 1;
 		index++;
 	}

 	xfers[index].rx_buf = val;
 	xfers[index].len = val_size;
 	index++;

 	return spi_sync_transfer(spi, xfers, index);
 }

 static int ocelot_spi_regmap_bus_write(void *context, const void *data, size_t count)
 {
 	struct device *dev = context;
 	struct spi_device *spi = to_spi_device(dev);

 	return spi_write(spi, data, count);
 }

 static const struct regmap_bus ocelot_spi_regmap_bus = {
 	.write = ocelot_spi_regmap_bus_write,
 	.read = ocelot_spi_regmap_bus_read,
 };

 struct regmap *ocelot_spi_init_regmap(struct device *dev, const struct resource *res)
 {
 	struct regmap_config regmap_config;

 	memcpy(&regmap_config, &ocelot_spi_regmap_config, sizeof(regmap_config));

 	regmap_config.name = res->name;
 	regmap_config.max_register = resource_size(res) - 1;
 	regmap_config.reg_base = res->start;

 	return devm_regmap_init(dev, &ocelot_spi_regmap_bus, dev, &regmap_config);
 }
 EXPORT_SYMBOL_NS(ocelot_spi_init_regmap, MFD_OCELOT_SPI);

 static int ocelot_spi_probe(struct spi_device *spi)
 {
 	struct device *dev = &spi->dev;
 	struct ocelot_ddata *ddata;
 	struct regmap *r;
 	int err;

 	ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
 	if (!ddata)
 		return -ENOMEM;

 	spi_set_drvdata(spi, ddata);

 	if (spi->max_speed_hz <= 500000) {
 		ddata->spi_padding_bytes = 0;
 	} else {
 		/*
 		 * Calculation taken from the manual for IF_CFGSTAT:IF_CFG.
 		 * Register access time is 1us, so we need to configure and send
 		 * out enough padding bytes between the read request and data
 		 * transmission that lasts at least 1 microsecond.
 		 */
 		ddata->spi_padding_bytes = 1 + (spi->max_speed_hz / HZ_PER_MHZ + 2) / 8;

 		ddata->dummy_buf = devm_kzalloc(dev, ddata->spi_padding_bytes, GFP_KERNEL);
 		if (!ddata->dummy_buf)
 			return -ENOMEM;
 	}

 	spi->bits_per_word = 8;

 	err = spi_setup(spi);
 	if (err)
 		return dev_err_probe(&spi->dev, err, "Error performing SPI setup\n");

 	r = ocelot_spi_init_regmap(dev, &vsc7512_dev_cpuorg_resource);
 	if (IS_ERR(r))
 		return PTR_ERR(r);

 	ddata->cpuorg_regmap = r;

 	r = ocelot_spi_init_regmap(dev, &vsc7512_gcb_resource);
 	if (IS_ERR(r))
 		return PTR_ERR(r);

 	ddata->gcb_regmap = r;

 	/*
 	 * The chip must be set up for SPI before it gets initialized and reset.
 	 * This must be done before calling init, and after a chip reset is
 	 * performed.
 	 */
 	err = ocelot_spi_initialize(dev);
 	if (err)
 		return dev_err_probe(dev, err, "Error initializing SPI bus\n");

 	err = ocelot_chip_reset(dev);
 	if (err)
 		return dev_err_probe(dev, err, "Error resetting device\n");

 	/*
 	 * A chip reset will clear the SPI configuration, so it needs to be done
 	 * again before we can access any registers.
 	 */
 	err = ocelot_spi_initialize(dev);
 	if (err)
 		return dev_err_probe(dev, err, "Error initializing SPI bus after reset\n");

 	err = ocelot_core_init(dev);
 	if (err)
 		return dev_err_probe(dev, err, "Error initializing Ocelot core\n");

 	return 0;
 }

 static const struct spi_device_id ocelot_spi_ids[] = {
 	{ "vsc7512", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(spi, ocelot_spi_ids);

 static const struct of_device_id ocelot_spi_of_match[] = {
 	{ .compatible = "mscc,vsc7512" },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, ocelot_spi_of_match);

 static struct spi_driver ocelot_spi_driver = {
 	.driver = {
 		.name = "ocelot-soc",
 		.of_match_table = ocelot_spi_of_match,
 	},
 	.id_table = ocelot_spi_ids,
 	.probe = ocelot_spi_probe,
 };
 module_spi_driver(ocelot_spi_driver);

 MODULE_DESCRIPTION("SPI Controlled Ocelot Chip Driver");
 MODULE_AUTHOR("Colin Foster <colin.foster@in-advantage.com>");
 MODULE_LICENSE("Dual MIT/GPL");
 MODULE_IMPORT_NS(MFD_OCELOT);
	// SPDX-License-Identifier: (GPL-2.0 OR MIT)
	/*
	* SPI core driver for the Ocelot chip family.
	*
	* This driver will handle everything necessary to allow for communication over
	* SPI to the VSC7511, VSC7512, VSC7513 and VSC7514 chips. The main functions
	* are to prepare the chip's SPI interface for a specific bus speed, and a host
	* processor's endianness. This will create and distribute regmaps for any
	* children.
	*
	* Copyright 2021-2022 Innovative Advantage Inc.
	*
	* Author: Colin Foster <colin.foster@in-advantage.com>
	*/

	#include <linux/device.h>
	#include <linux/err.h>
	#include <linux/errno.h>
	#include <linux/export.h>
	#include <linux/ioport.h>
	#include <linux/mod_devicetable.h>
	#include <linux/module.h>
	#include <linux/regmap.h>
	#include <linux/spi/spi.h>
	#include <linux/types.h>
	#include <linux/units.h>

	#include "ocelot.h"

	#define REG_DEV_CPUORG_IF_CTRL 0x0000
	#define REG_DEV_CPUORG_IF_CFGSTAT 0x0004

	#define CFGSTAT_IF_NUM_VCORE (0 << 24)
	#define CFGSTAT_IF_NUM_VRAP (1 << 24)
	#define CFGSTAT_IF_NUM_SI (2 << 24)
	#define CFGSTAT_IF_NUM_MIIM (3 << 24)

	#define VSC7512_DEVCPU_ORG_RES_START 0x71000000
	#define VSC7512_DEVCPU_ORG_RES_SIZE 0x38

	#define VSC7512_CHIP_REGS_RES_START 0x71070000
	#define VSC7512_CHIP_REGS_RES_SIZE 0x14

	static const struct resource vsc7512_dev_cpuorg_resource =
	DEFINE_RES_REG_NAMED(VSC7512_DEVCPU_ORG_RES_START,
	VSC7512_DEVCPU_ORG_RES_SIZE,
	"devcpu_org");

	static const struct resource vsc7512_gcb_resource =
	DEFINE_RES_REG_NAMED(VSC7512_CHIP_REGS_RES_START,
	VSC7512_CHIP_REGS_RES_SIZE,
	"devcpu_gcb_chip_regs");

	static int ocelot_spi_initialize(struct device *dev)
	{
	struct ocelot_ddata *ddata = dev_get_drvdata(dev);
	u32 val, check;
	int err;

	val = OCELOT_SPI_BYTE_ORDER;

	/*
	* The SPI address must be big-endian, but we want the payload to match
	* our CPU. These are two bits (0 and 1) but they're repeated such that
	* the write from any configuration will be valid. The four
	* configurations are:
	*
	* 0b00: little-endian, MSB first
	* \| 111111 \| 22221111 \| 33222222 \|
	* \| 76543210 \| 54321098 \| 32109876 \| 10987654 \|
	*
	* 0b01: big-endian, MSB first
	* \| 33222222 \| 22221111 \| 111111 \| \|
	* \| 10987654 \| 32109876 \| 54321098 \| 76543210 \|
	*
	* 0b10: little-endian, LSB first
	* \| 111111 \| 11112222 \| 22222233 \|
	* \| 01234567 \| 89012345 \| 67890123 \| 45678901 \|
	*
	* 0b11: big-endian, LSB first
	* \| 22222233 \| 11112222 \| 111111 \| \|
	* \| 45678901 \| 67890123 \| 89012345 \| 01234567 \|
	*/
	err = regmap_write(ddata->cpuorg_regmap, REG_DEV_CPUORG_IF_CTRL, val);
	if (err)
	return err;

	/*
	* Apply the number of padding bytes between a read request and the data
	* payload. Some registers have access times of up to 1us, so if the
	* first payload bit is shifted out too quickly, the read will fail.
	*/
	val = ddata->spi_padding_bytes;
	err = regmap_write(ddata->cpuorg_regmap, REG_DEV_CPUORG_IF_CFGSTAT, val);
	if (err)
	return err;

	/*
	* After we write the interface configuration, read it back here. This
	* will verify several different things. The first is that the number of
	* padding bytes actually got written correctly. These are found in bits
	* 0:3.
	*
	* The second is that bit 16 is cleared. Bit 16 is IF_CFGSTAT:IF_STAT,
	* and will be set if the register access is too fast. This would be in
	* the condition that the number of padding bytes is insufficient for
	* the SPI bus frequency.
	*
	* The last check is for bits 31:24, which define the interface by which
	* the registers are being accessed. Since we're accessing them via the
	* serial interface, it must return IF_NUM_SI.
	*/
	check = val \| CFGSTAT_IF_NUM_SI;

	err = regmap_read(ddata->cpuorg_regmap, REG_DEV_CPUORG_IF_CFGSTAT, &val);
	if (err)
	return err;

	if (check != val)
	return -ENODEV;

	return 0;
	}

	static const struct regmap_config ocelot_spi_regmap_config = {
	.reg_bits = 24,
	.reg_stride = 4,
	.reg_shift = REGMAP_DOWNSHIFT(2),
	.val_bits = 32,

	.write_flag_mask = 0x80,

	.use_single_read = true,
	.use_single_write = true,
	.can_multi_write = false,

	.reg_format_endian = REGMAP_ENDIAN_BIG,
	.val_format_endian = REGMAP_ENDIAN_NATIVE,
	};

	static int ocelot_spi_regmap_bus_read(void context, const void reg, size_t reg_size,
	void *val, size_t val_size)
	{
	struct spi_transfer xfers[3] = {0};
	struct device *dev = context;
	struct ocelot_ddata *ddata;
	struct spi_device *spi;
	unsigned int index = 0;

	ddata = dev_get_drvdata(dev);
	spi = to_spi_device(dev);

	xfers[index].tx_buf = reg;
	xfers[index].len = reg_size;
	index++;

	if (ddata->spi_padding_bytes) {
	xfers[index].len = ddata->spi_padding_bytes;
	xfers[index].tx_buf = ddata->dummy_buf;
	xfers[index].dummy_data = 1;
	index++;
	}

	xfers[index].rx_buf = val;
	xfers[index].len = val_size;
	index++;

	return spi_sync_transfer(spi, xfers, index);
	}

	static int ocelot_spi_regmap_bus_write(void context, const void data, size_t count)
	{
	struct device *dev = context;
	struct spi_device *spi = to_spi_device(dev);

	return spi_write(spi, data, count);
	}

	static const struct regmap_bus ocelot_spi_regmap_bus = {
	.write = ocelot_spi_regmap_bus_write,
	.read = ocelot_spi_regmap_bus_read,
	};

	struct regmap ocelot_spi_init_regmap(struct device dev, const struct resource *res)
	{
	struct regmap_config regmap_config;

	memcpy(&regmap_config, &ocelot_spi_regmap_config, sizeof(regmap_config));

	regmap_config.name = res->name;
	regmap_config.max_register = resource_size(res) - 1;
	regmap_config.reg_base = res->start;

	return devm_regmap_init(dev, &ocelot_spi_regmap_bus, dev, &regmap_config);
	}
	EXPORT_SYMBOL_NS(ocelot_spi_init_regmap, MFD_OCELOT_SPI);

	static int ocelot_spi_probe(struct spi_device *spi)
	{
	struct device *dev = &spi->dev;
	struct ocelot_ddata *ddata;
	struct regmap *r;
	int err;

	ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
	if (!ddata)
	return -ENOMEM;

	spi_set_drvdata(spi, ddata);

	if (spi->max_speed_hz <= 500000) {
	ddata->spi_padding_bytes = 0;
	} else {
	/*
	* Calculation taken from the manual for IF_CFGSTAT:IF_CFG.
	* Register access time is 1us, so we need to configure and send
	* out enough padding bytes between the read request and data
	* transmission that lasts at least 1 microsecond.
	*/
	ddata->spi_padding_bytes = 1 + (spi->max_speed_hz / HZ_PER_MHZ + 2) / 8;

	ddata->dummy_buf = devm_kzalloc(dev, ddata->spi_padding_bytes, GFP_KERNEL);
	if (!ddata->dummy_buf)
	return -ENOMEM;
	}

	spi->bits_per_word = 8;

	err = spi_setup(spi);
	if (err)
	return dev_err_probe(&spi->dev, err, "Error performing SPI setup\n");

	r = ocelot_spi_init_regmap(dev, &vsc7512_dev_cpuorg_resource);
	if (IS_ERR(r))
	return PTR_ERR(r);

	ddata->cpuorg_regmap = r;

	r = ocelot_spi_init_regmap(dev, &vsc7512_gcb_resource);
	if (IS_ERR(r))
	return PTR_ERR(r);

	ddata->gcb_regmap = r;

	/*
	* The chip must be set up for SPI before it gets initialized and reset.
	* This must be done before calling init, and after a chip reset is
	* performed.
	*/
	err = ocelot_spi_initialize(dev);
	if (err)
	return dev_err_probe(dev, err, "Error initializing SPI bus\n");

	err = ocelot_chip_reset(dev);
	if (err)
	return dev_err_probe(dev, err, "Error resetting device\n");

	/*
	* A chip reset will clear the SPI configuration, so it needs to be done
	* again before we can access any registers.
	*/
	err = ocelot_spi_initialize(dev);
	if (err)
	return dev_err_probe(dev, err, "Error initializing SPI bus after reset\n");

	err = ocelot_core_init(dev);
	if (err)
	return dev_err_probe(dev, err, "Error initializing Ocelot core\n");

	return 0;
	}

	static const struct spi_device_id ocelot_spi_ids[] = {
	{ "vsc7512", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(spi, ocelot_spi_ids);

	static const struct of_device_id ocelot_spi_of_match[] = {
	{ .compatible = "mscc,vsc7512" },
	{ }
	};
	MODULE_DEVICE_TABLE(of, ocelot_spi_of_match);

	static struct spi_driver ocelot_spi_driver = {
	.driver = {
	.name = "ocelot-soc",
	.of_match_table = ocelot_spi_of_match,
	},
	.id_table = ocelot_spi_ids,
	.probe = ocelot_spi_probe,
	};
	module_spi_driver(ocelot_spi_driver);

	MODULE_DESCRIPTION("SPI Controlled Ocelot Chip Driver");
	MODULE_AUTHOR("Colin Foster <colin.foster@in-advantage.com>");
	MODULE_LICENSE("Dual MIT/GPL");
	MODULE_IMPORT_NS(MFD_OCELOT);