drivers/net/phy/spi_ks8995.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * SPI driver for Micrel/Kendin KS8995M and KSZ8864RMN ethernet switches
  *
  * Copyright (C) 2008 Gabor Juhos <juhosg at openwrt.org>
  *
  * This file was based on: drivers/spi/at25.c
  *     Copyright (C) 2006 David Brownell
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/gpio/consumer.h>
 #include <linux/of.h>

 #include <linux/spi/spi.h>

 #define DRV_VERSION		"0.1.1"
 #define DRV_DESC		"Micrel KS8995 Ethernet switch SPI driver"

 /* ------------------------------------------------------------------------ */

 #define KS8995_REG_ID0		0x00    /* Chip ID0 */
 #define KS8995_REG_ID1		0x01    /* Chip ID1 */

 #define KS8995_REG_GC0		0x02    /* Global Control 0 */
 #define KS8995_REG_GC1		0x03    /* Global Control 1 */
 #define KS8995_REG_GC2		0x04    /* Global Control 2 */
 #define KS8995_REG_GC3		0x05    /* Global Control 3 */
 #define KS8995_REG_GC4		0x06    /* Global Control 4 */
 #define KS8995_REG_GC5		0x07    /* Global Control 5 */
 #define KS8995_REG_GC6		0x08    /* Global Control 6 */
 #define KS8995_REG_GC7		0x09    /* Global Control 7 */
 #define KS8995_REG_GC8		0x0a    /* Global Control 8 */
 #define KS8995_REG_GC9		0x0b    /* Global Control 9 */

 #define KS8995_REG_PC(p, r)	((0x10 * p) + r)	 /* Port Control */
 #define KS8995_REG_PS(p, r)	((0x10 * p) + r + 0xe)  /* Port Status */

 #define KS8995_REG_TPC0		0x60    /* TOS Priority Control 0 */
 #define KS8995_REG_TPC1		0x61    /* TOS Priority Control 1 */
 #define KS8995_REG_TPC2		0x62    /* TOS Priority Control 2 */
 #define KS8995_REG_TPC3		0x63    /* TOS Priority Control 3 */
 #define KS8995_REG_TPC4		0x64    /* TOS Priority Control 4 */
 #define KS8995_REG_TPC5		0x65    /* TOS Priority Control 5 */
 #define KS8995_REG_TPC6		0x66    /* TOS Priority Control 6 */
 #define KS8995_REG_TPC7		0x67    /* TOS Priority Control 7 */

 #define KS8995_REG_MAC0		0x68    /* MAC address 0 */
 #define KS8995_REG_MAC1		0x69    /* MAC address 1 */
 #define KS8995_REG_MAC2		0x6a    /* MAC address 2 */
 #define KS8995_REG_MAC3		0x6b    /* MAC address 3 */
 #define KS8995_REG_MAC4		0x6c    /* MAC address 4 */
 #define KS8995_REG_MAC5		0x6d    /* MAC address 5 */

 #define KS8995_REG_IAC0		0x6e    /* Indirect Access Control 0 */
 #define KS8995_REG_IAC1		0x6f    /* Indirect Access Control 0 */
 #define KS8995_REG_IAD7		0x70    /* Indirect Access Data 7 */
 #define KS8995_REG_IAD6		0x71    /* Indirect Access Data 6 */
 #define KS8995_REG_IAD5		0x72    /* Indirect Access Data 5 */
 #define KS8995_REG_IAD4		0x73    /* Indirect Access Data 4 */
 #define KS8995_REG_IAD3		0x74    /* Indirect Access Data 3 */
 #define KS8995_REG_IAD2		0x75    /* Indirect Access Data 2 */
 #define KS8995_REG_IAD1		0x76    /* Indirect Access Data 1 */
 #define KS8995_REG_IAD0		0x77    /* Indirect Access Data 0 */

 #define KSZ8864_REG_ID1		0xfe	/* Chip ID in bit 7 */

 #define KS8995_REGS_SIZE	0x80
 #define KSZ8864_REGS_SIZE	0x100
 #define KSZ8795_REGS_SIZE	0x100

 #define ID1_CHIPID_M		0xf
 #define ID1_CHIPID_S		4
 #define ID1_REVISION_M		0x7
 #define ID1_REVISION_S		1
 #define ID1_START_SW		1	/* start the switch */

 #define FAMILY_KS8995		0x95
 #define FAMILY_KSZ8795		0x87
 #define CHIPID_M		0
 #define KS8995_CHIP_ID		0x00
 #define KSZ8864_CHIP_ID		0x01
 #define KSZ8795_CHIP_ID		0x09

 #define KS8995_CMD_WRITE	0x02U
 #define KS8995_CMD_READ		0x03U

 #define KS8995_RESET_DELAY	10 /* usec */

 enum ks8995_chip_variant {
 	ks8995,
 	ksz8864,
 	ksz8795,
 	max_variant
 };

 struct ks8995_chip_params {
 	char *name;
 	int family_id;
 	int chip_id;
 	int regs_size;
 	int addr_width;
 	int addr_shift;
 };

 static const struct ks8995_chip_params ks8995_chip[] = {
 	[ks8995] = {
 		.name = "KS8995MA",
 		.family_id = FAMILY_KS8995,
 		.chip_id = KS8995_CHIP_ID,
 		.regs_size = KS8995_REGS_SIZE,
 		.addr_width = 8,
 		.addr_shift = 0,
 	},
 	[ksz8864] = {
 		.name = "KSZ8864RMN",
 		.family_id = FAMILY_KS8995,
 		.chip_id = KSZ8864_CHIP_ID,
 		.regs_size = KSZ8864_REGS_SIZE,
 		.addr_width = 8,
 		.addr_shift = 0,
 	},
 	[ksz8795] = {
 		.name = "KSZ8795CLX",
 		.family_id = FAMILY_KSZ8795,
 		.chip_id = KSZ8795_CHIP_ID,
 		.regs_size = KSZ8795_REGS_SIZE,
 		.addr_width = 12,
 		.addr_shift = 1,
 	},
 };

 struct ks8995_switch {
 	struct spi_device	*spi;
 	struct mutex		lock;
 	struct gpio_desc	*reset_gpio;
 	struct bin_attribute	regs_attr;
 	const struct ks8995_chip_params	*chip;
 	int			revision_id;
 };

 static const struct spi_device_id ks8995_id[] = {
 	{"ks8995", ks8995},
 	{"ksz8864", ksz8864},
 	{"ksz8795", ksz8795},
 	{ }
 };
 MODULE_DEVICE_TABLE(spi, ks8995_id);

 static const struct of_device_id ks8895_spi_of_match[] = {
 	{ .compatible = "micrel,ks8995" },
 	{ .compatible = "micrel,ksz8864" },
 	{ .compatible = "micrel,ksz8795" },
 	{ },
 };
 MODULE_DEVICE_TABLE(of, ks8895_spi_of_match);

 static inline u8 get_chip_id(u8 val)
 {
 	return (val >> ID1_CHIPID_S) & ID1_CHIPID_M;
 }

 static inline u8 get_chip_rev(u8 val)
 {
 	return (val >> ID1_REVISION_S) & ID1_REVISION_M;
 }

 /* create_spi_cmd - create a chip specific SPI command header
  * @ks: pointer to switch instance
  * @cmd: SPI command for switch
  * @address: register address for command
  *
  * Different chip families use different bit pattern to address the switches
  * registers:
  *
  * KS8995: 8bit command + 8bit address
  * KSZ8795: 3bit command + 12bit address + 1bit TR (?)
  */
 static inline __be16 create_spi_cmd(struct ks8995_switch *ks, int cmd,
 				    unsigned address)
 {
 	u16 result = cmd;

 	/* make room for address (incl. address shift) */
 	result <<= ks->chip->addr_width + ks->chip->addr_shift;
 	/* add address */
 	result |= address << ks->chip->addr_shift;
 	/* SPI protocol needs big endian */
 	return cpu_to_be16(result);
 }
 /* ------------------------------------------------------------------------ */
 static int ks8995_read(struct ks8995_switch *ks, char *buf,
 		 unsigned offset, size_t count)
 {
 	__be16 cmd;
 	struct spi_transfer t[2];
 	struct spi_message m;
 	int err;

 	cmd = create_spi_cmd(ks, KS8995_CMD_READ, offset);
 	spi_message_init(&m);

 	memset(&t, 0, sizeof(t));

 	t[0].tx_buf = &cmd;
 	t[0].len = sizeof(cmd);
 	spi_message_add_tail(&t[0], &m);

 	t[1].rx_buf = buf;
 	t[1].len = count;
 	spi_message_add_tail(&t[1], &m);

 	mutex_lock(&ks->lock);
 	err = spi_sync(ks->spi, &m);
 	mutex_unlock(&ks->lock);

 	return err ? err : count;
 }

 static int ks8995_write(struct ks8995_switch *ks, char *buf,
 		 unsigned offset, size_t count)
 {
 	__be16 cmd;
 	struct spi_transfer t[2];
 	struct spi_message m;
 	int err;

 	cmd = create_spi_cmd(ks, KS8995_CMD_WRITE, offset);
 	spi_message_init(&m);

 	memset(&t, 0, sizeof(t));

 	t[0].tx_buf = &cmd;
 	t[0].len = sizeof(cmd);
 	spi_message_add_tail(&t[0], &m);

 	t[1].tx_buf = buf;
 	t[1].len = count;
 	spi_message_add_tail(&t[1], &m);

 	mutex_lock(&ks->lock);
 	err = spi_sync(ks->spi, &m);
 	mutex_unlock(&ks->lock);

 	return err ? err : count;
 }

 static inline int ks8995_read_reg(struct ks8995_switch *ks, u8 addr, u8 *buf)
 {
 	return ks8995_read(ks, buf, addr, 1) != 1;
 }

 static inline int ks8995_write_reg(struct ks8995_switch *ks, u8 addr, u8 val)
 {
 	char buf = val;

 	return ks8995_write(ks, &buf, addr, 1) != 1;
 }

 /* ------------------------------------------------------------------------ */

 static int ks8995_stop(struct ks8995_switch *ks)
 {
 	return ks8995_write_reg(ks, KS8995_REG_ID1, 0);
 }

 static int ks8995_start(struct ks8995_switch *ks)
 {
 	return ks8995_write_reg(ks, KS8995_REG_ID1, 1);
 }

 static int ks8995_reset(struct ks8995_switch *ks)
 {
 	int err;

 	err = ks8995_stop(ks);
 	if (err)
 		return err;

 	udelay(KS8995_RESET_DELAY);

 	return ks8995_start(ks);
 }

 static ssize_t ks8995_registers_read(struct file *filp, struct kobject *kobj,
 	struct bin_attribute *bin_attr, char *buf, loff_t off, size_t count)
 {
 	struct device *dev;
 	struct ks8995_switch *ks8995;

 	dev = kobj_to_dev(kobj);
 	ks8995 = dev_get_drvdata(dev);

 	return ks8995_read(ks8995, buf, off, count);
 }

 static ssize_t ks8995_registers_write(struct file *filp, struct kobject *kobj,
 	struct bin_attribute *bin_attr, char *buf, loff_t off, size_t count)
 {
 	struct device *dev;
 	struct ks8995_switch *ks8995;

 	dev = kobj_to_dev(kobj);
 	ks8995 = dev_get_drvdata(dev);

 	return ks8995_write(ks8995, buf, off, count);
 }

 /* ks8995_get_revision - get chip revision
  * @ks: pointer to switch instance
  *
  * Verify chip family and id and get chip revision.
  */
 static int ks8995_get_revision(struct ks8995_switch *ks)
 {
 	int err;
 	u8 id0, id1, ksz8864_id;

 	/* read family id */
 	err = ks8995_read_reg(ks, KS8995_REG_ID0, &id0);
 	if (err) {
 		err = -EIO;
 		goto err_out;
 	}

 	/* verify family id */
 	if (id0 != ks->chip->family_id) {
 		dev_err(&ks->spi->dev, "chip family id mismatch: expected 0x%02x but 0x%02x read\n",
 			ks->chip->family_id, id0);
 		err = -ENODEV;
 		goto err_out;
 	}

 	switch (ks->chip->family_id) {
 	case FAMILY_KS8995:
 		/* try reading chip id at CHIP ID1 */
 		err = ks8995_read_reg(ks, KS8995_REG_ID1, &id1);
 		if (err) {
 			err = -EIO;
 			goto err_out;
 		}

 		/* verify chip id */
 		if ((get_chip_id(id1) == CHIPID_M) &&
 		    (get_chip_id(id1) == ks->chip->chip_id)) {
 			/* KS8995MA */
 			ks->revision_id = get_chip_rev(id1);
 		} else if (get_chip_id(id1) != CHIPID_M) {
 			/* KSZ8864RMN */
 			err = ks8995_read_reg(ks, KS8995_REG_ID1, &ksz8864_id);
 			if (err) {
 				err = -EIO;
 				goto err_out;
 			}

 			if ((ksz8864_id & 0x80) &&
 			    (ks->chip->chip_id == KSZ8864_CHIP_ID)) {
 				ks->revision_id = get_chip_rev(id1);
 			}

 		} else {
 			dev_err(&ks->spi->dev, "unsupported chip id for KS8995 family: 0x%02x\n",
 				id1);
 			err = -ENODEV;
 		}
 		break;
 	case FAMILY_KSZ8795:
 		/* try reading chip id at CHIP ID1 */
 		err = ks8995_read_reg(ks, KS8995_REG_ID1, &id1);
 		if (err) {
 			err = -EIO;
 			goto err_out;
 		}

 		if (get_chip_id(id1) == ks->chip->chip_id) {
 			ks->revision_id = get_chip_rev(id1);
 		} else {
 			dev_err(&ks->spi->dev, "unsupported chip id for KSZ8795 family: 0x%02x\n",
 				id1);
 			err = -ENODEV;
 		}
 		break;
 	default:
 		dev_err(&ks->spi->dev, "unsupported family id: 0x%02x\n", id0);
 		err = -ENODEV;
 		break;
 	}
 err_out:
 	return err;
 }

 static const struct bin_attribute ks8995_registers_attr = {
 	.attr = {
 		.name   = "registers",
 		.mode   = 0600,
 	},
 	.size   = KS8995_REGS_SIZE,
 	.read   = ks8995_registers_read,
 	.write  = ks8995_registers_write,
 };

 /* ------------------------------------------------------------------------ */
 static int ks8995_probe(struct spi_device *spi)
 {
 	struct ks8995_switch *ks;
 	int err;
 	int variant = spi_get_device_id(spi)->driver_data;

 	if (variant >= max_variant) {
 		dev_err(&spi->dev, "bad chip variant %d\n", variant);
 		return -ENODEV;
 	}

 	ks = devm_kzalloc(&spi->dev, sizeof(*ks), GFP_KERNEL);
 	if (!ks)
 		return -ENOMEM;

 	mutex_init(&ks->lock);
 	ks->spi = spi;
 	ks->chip = &ks8995_chip[variant];

 	ks->reset_gpio = devm_gpiod_get_optional(&spi->dev, "reset",
 						 GPIOD_OUT_HIGH);
 	err = PTR_ERR_OR_ZERO(ks->reset_gpio);
 	if (err) {
 		dev_err(&spi->dev,
 			"failed to get reset gpio: %d\n", err);
 		return err;
 	}

 	err = gpiod_set_consumer_name(ks->reset_gpio, "switch-reset");
 	if (err)
 		return err;

 	/* de-assert switch reset */
 	/* FIXME: this likely requires a delay */
 	gpiod_set_value_cansleep(ks->reset_gpio, 0);

 	spi_set_drvdata(spi, ks);

 	spi->mode = SPI_MODE_0;
 	spi->bits_per_word = 8;
 	err = spi_setup(spi);
 	if (err) {
 		dev_err(&spi->dev, "spi_setup failed, err=%d\n", err);
 		return err;
 	}

 	err = ks8995_get_revision(ks);
 	if (err)
 		return err;

 	memcpy(&ks->regs_attr, &ks8995_registers_attr, sizeof(ks->regs_attr));
 	ks->regs_attr.size = ks->chip->regs_size;

 	err = ks8995_reset(ks);
 	if (err)
 		return err;

 	sysfs_attr_init(&ks->regs_attr.attr);
 	err = sysfs_create_bin_file(&spi->dev.kobj, &ks->regs_attr);
 	if (err) {
 		dev_err(&spi->dev, "unable to create sysfs file, err=%d\n",
 				    err);
 		return err;
 	}

 	dev_info(&spi->dev, "%s device found, Chip ID:%x, Revision:%x\n",
 		 ks->chip->name, ks->chip->chip_id, ks->revision_id);

 	return 0;
 }

 static void ks8995_remove(struct spi_device *spi)
 {
 	struct ks8995_switch *ks = spi_get_drvdata(spi);

 	sysfs_remove_bin_file(&spi->dev.kobj, &ks->regs_attr);

 	/* assert reset */
 	gpiod_set_value_cansleep(ks->reset_gpio, 1);
 }

 /* ------------------------------------------------------------------------ */
 static struct spi_driver ks8995_driver = {
 	.driver = {
 		.name	    = "spi-ks8995",
 		.of_match_table = ks8895_spi_of_match,
 	},
 	.probe	  = ks8995_probe,
 	.remove	  = ks8995_remove,
 	.id_table = ks8995_id,
 };

 module_spi_driver(ks8995_driver);

 MODULE_DESCRIPTION(DRV_DESC);
 MODULE_VERSION(DRV_VERSION);
 MODULE_AUTHOR("Gabor Juhos <juhosg at openwrt.org>");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* SPI driver for Micrel/Kendin KS8995M and KSZ8864RMN ethernet switches
	*
	* Copyright (C) 2008 Gabor Juhos <juhosg at openwrt.org>
	*
	* This file was based on: drivers/spi/at25.c
	* Copyright (C) 2006 David Brownell
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/types.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/delay.h>
	#include <linux/device.h>
	#include <linux/gpio/consumer.h>
	#include <linux/of.h>

	#include <linux/spi/spi.h>

	#define DRV_VERSION "0.1.1"
	#define DRV_DESC "Micrel KS8995 Ethernet switch SPI driver"

	/* ------------------------------------------------------------------------ */

	#define KS8995_REG_ID0 0x00 /* Chip ID0 */
	#define KS8995_REG_ID1 0x01 /* Chip ID1 */

	#define KS8995_REG_GC0 0x02 /* Global Control 0 */
	#define KS8995_REG_GC1 0x03 /* Global Control 1 */
	#define KS8995_REG_GC2 0x04 /* Global Control 2 */
	#define KS8995_REG_GC3 0x05 /* Global Control 3 */
	#define KS8995_REG_GC4 0x06 /* Global Control 4 */
	#define KS8995_REG_GC5 0x07 /* Global Control 5 */
	#define KS8995_REG_GC6 0x08 /* Global Control 6 */
	#define KS8995_REG_GC7 0x09 /* Global Control 7 */
	#define KS8995_REG_GC8 0x0a /* Global Control 8 */
	#define KS8995_REG_GC9 0x0b /* Global Control 9 */

	#define KS8995_REG_PC(p, r) ((0x10 * p) + r) /* Port Control */
	#define KS8995_REG_PS(p, r) ((0x10 * p) + r + 0xe) /* Port Status */

	#define KS8995_REG_TPC0 0x60 /* TOS Priority Control 0 */
	#define KS8995_REG_TPC1 0x61 /* TOS Priority Control 1 */
	#define KS8995_REG_TPC2 0x62 /* TOS Priority Control 2 */
	#define KS8995_REG_TPC3 0x63 /* TOS Priority Control 3 */
	#define KS8995_REG_TPC4 0x64 /* TOS Priority Control 4 */
	#define KS8995_REG_TPC5 0x65 /* TOS Priority Control 5 */
	#define KS8995_REG_TPC6 0x66 /* TOS Priority Control 6 */
	#define KS8995_REG_TPC7 0x67 /* TOS Priority Control 7 */

	#define KS8995_REG_MAC0 0x68 /* MAC address 0 */
	#define KS8995_REG_MAC1 0x69 /* MAC address 1 */
	#define KS8995_REG_MAC2 0x6a /* MAC address 2 */
	#define KS8995_REG_MAC3 0x6b /* MAC address 3 */
	#define KS8995_REG_MAC4 0x6c /* MAC address 4 */
	#define KS8995_REG_MAC5 0x6d /* MAC address 5 */

	#define KS8995_REG_IAC0 0x6e /* Indirect Access Control 0 */
	#define KS8995_REG_IAC1 0x6f /* Indirect Access Control 0 */
	#define KS8995_REG_IAD7 0x70 /* Indirect Access Data 7 */
	#define KS8995_REG_IAD6 0x71 /* Indirect Access Data 6 */
	#define KS8995_REG_IAD5 0x72 /* Indirect Access Data 5 */
	#define KS8995_REG_IAD4 0x73 /* Indirect Access Data 4 */
	#define KS8995_REG_IAD3 0x74 /* Indirect Access Data 3 */
	#define KS8995_REG_IAD2 0x75 /* Indirect Access Data 2 */
	#define KS8995_REG_IAD1 0x76 /* Indirect Access Data 1 */
	#define KS8995_REG_IAD0 0x77 /* Indirect Access Data 0 */

	#define KSZ8864_REG_ID1 0xfe /* Chip ID in bit 7 */

	#define KS8995_REGS_SIZE 0x80
	#define KSZ8864_REGS_SIZE 0x100
	#define KSZ8795_REGS_SIZE 0x100

	#define ID1_CHIPID_M 0xf
	#define ID1_CHIPID_S 4
	#define ID1_REVISION_M 0x7
	#define ID1_REVISION_S 1
	#define ID1_START_SW 1 /* start the switch */

	#define FAMILY_KS8995 0x95
	#define FAMILY_KSZ8795 0x87
	#define CHIPID_M 0
	#define KS8995_CHIP_ID 0x00
	#define KSZ8864_CHIP_ID 0x01
	#define KSZ8795_CHIP_ID 0x09

	#define KS8995_CMD_WRITE 0x02U
	#define KS8995_CMD_READ 0x03U

	#define KS8995_RESET_DELAY 10 /* usec */

	enum ks8995_chip_variant {
	ks8995,
	ksz8864,
	ksz8795,
	max_variant
	};

	struct ks8995_chip_params {
	char *name;
	int family_id;
	int chip_id;
	int regs_size;
	int addr_width;
	int addr_shift;
	};

	static const struct ks8995_chip_params ks8995_chip[] = {
	[ks8995] = {
	.name = "KS8995MA",
	.family_id = FAMILY_KS8995,
	.chip_id = KS8995_CHIP_ID,
	.regs_size = KS8995_REGS_SIZE,
	.addr_width = 8,
	.addr_shift = 0,
	},
	[ksz8864] = {
	.name = "KSZ8864RMN",
	.family_id = FAMILY_KS8995,
	.chip_id = KSZ8864_CHIP_ID,
	.regs_size = KSZ8864_REGS_SIZE,
	.addr_width = 8,
	.addr_shift = 0,
	},
	[ksz8795] = {
	.name = "KSZ8795CLX",
	.family_id = FAMILY_KSZ8795,
	.chip_id = KSZ8795_CHIP_ID,
	.regs_size = KSZ8795_REGS_SIZE,
	.addr_width = 12,
	.addr_shift = 1,
	},
	};

	struct ks8995_switch {
	struct spi_device *spi;
	struct mutex lock;
	struct gpio_desc *reset_gpio;
	struct bin_attribute regs_attr;
	const struct ks8995_chip_params *chip;
	int revision_id;
	};

	static const struct spi_device_id ks8995_id[] = {
	{"ks8995", ks8995},
	{"ksz8864", ksz8864},
	{"ksz8795", ksz8795},
	{ }
	};
	MODULE_DEVICE_TABLE(spi, ks8995_id);

	static const struct of_device_id ks8895_spi_of_match[] = {
	{ .compatible = "micrel,ks8995" },
	{ .compatible = "micrel,ksz8864" },
	{ .compatible = "micrel,ksz8795" },
	{ },
	};
	MODULE_DEVICE_TABLE(of, ks8895_spi_of_match);

	static inline u8 get_chip_id(u8 val)
	{
	return (val >> ID1_CHIPID_S) & ID1_CHIPID_M;
	}

	static inline u8 get_chip_rev(u8 val)
	{
	return (val >> ID1_REVISION_S) & ID1_REVISION_M;
	}

	/* create_spi_cmd - create a chip specific SPI command header
	* @ks: pointer to switch instance
	* @cmd: SPI command for switch
	* @address: register address for command
	*
	* Different chip families use different bit pattern to address the switches
	* registers:
	*
	* KS8995: 8bit command + 8bit address
	* KSZ8795: 3bit command + 12bit address + 1bit TR (?)
	*/
	static inline __be16 create_spi_cmd(struct ks8995_switch *ks, int cmd,
	unsigned address)
	{
	u16 result = cmd;

	/* make room for address (incl. address shift) */
	result <<= ks->chip->addr_width + ks->chip->addr_shift;
	/* add address */
	result \|= address << ks->chip->addr_shift;
	/* SPI protocol needs big endian */
	return cpu_to_be16(result);
	}
	/* ------------------------------------------------------------------------ */
	static int ks8995_read(struct ks8995_switch ks, char buf,
	unsigned offset, size_t count)
	{
	__be16 cmd;
	struct spi_transfer t[2];
	struct spi_message m;
	int err;

	cmd = create_spi_cmd(ks, KS8995_CMD_READ, offset);
	spi_message_init(&m);

	memset(&t, 0, sizeof(t));

	t[0].tx_buf = &cmd;
	t[0].len = sizeof(cmd);
	spi_message_add_tail(&t[0], &m);

	t[1].rx_buf = buf;
	t[1].len = count;
	spi_message_add_tail(&t[1], &m);

	mutex_lock(&ks->lock);
	err = spi_sync(ks->spi, &m);
	mutex_unlock(&ks->lock);

	return err ? err : count;
	}

	static int ks8995_write(struct ks8995_switch ks, char buf,
	unsigned offset, size_t count)
	{
	__be16 cmd;
	struct spi_transfer t[2];
	struct spi_message m;
	int err;

	cmd = create_spi_cmd(ks, KS8995_CMD_WRITE, offset);
	spi_message_init(&m);

	memset(&t, 0, sizeof(t));

	t[0].tx_buf = &cmd;
	t[0].len = sizeof(cmd);
	spi_message_add_tail(&t[0], &m);

	t[1].tx_buf = buf;
	t[1].len = count;
	spi_message_add_tail(&t[1], &m);

	mutex_lock(&ks->lock);
	err = spi_sync(ks->spi, &m);
	mutex_unlock(&ks->lock);

	return err ? err : count;
	}

	static inline int ks8995_read_reg(struct ks8995_switch ks, u8 addr, u8 buf)
	{
	return ks8995_read(ks, buf, addr, 1) != 1;
	}

	static inline int ks8995_write_reg(struct ks8995_switch *ks, u8 addr, u8 val)
	{
	char buf = val;

	return ks8995_write(ks, &buf, addr, 1) != 1;
	}

	/* ------------------------------------------------------------------------ */

	static int ks8995_stop(struct ks8995_switch *ks)
	{
	return ks8995_write_reg(ks, KS8995_REG_ID1, 0);
	}

	static int ks8995_start(struct ks8995_switch *ks)
	{
	return ks8995_write_reg(ks, KS8995_REG_ID1, 1);
	}

	static int ks8995_reset(struct ks8995_switch *ks)
	{
	int err;

	err = ks8995_stop(ks);
	if (err)
	return err;

	udelay(KS8995_RESET_DELAY);

	return ks8995_start(ks);
	}

	static ssize_t ks8995_registers_read(struct file filp, struct kobject kobj,
	struct bin_attribute bin_attr, char buf, loff_t off, size_t count)
	{
	struct device *dev;
	struct ks8995_switch *ks8995;

	dev = kobj_to_dev(kobj);
	ks8995 = dev_get_drvdata(dev);

	return ks8995_read(ks8995, buf, off, count);
	}

	static ssize_t ks8995_registers_write(struct file filp, struct kobject kobj,
	struct bin_attribute bin_attr, char buf, loff_t off, size_t count)
	{
	struct device *dev;
	struct ks8995_switch *ks8995;

	dev = kobj_to_dev(kobj);
	ks8995 = dev_get_drvdata(dev);

	return ks8995_write(ks8995, buf, off, count);
	}

	/* ks8995_get_revision - get chip revision
	* @ks: pointer to switch instance
	*
	* Verify chip family and id and get chip revision.
	*/
	static int ks8995_get_revision(struct ks8995_switch *ks)
	{
	int err;
	u8 id0, id1, ksz8864_id;

	/* read family id */
	err = ks8995_read_reg(ks, KS8995_REG_ID0, &id0);
	if (err) {
	err = -EIO;
	goto err_out;
	}

	/* verify family id */
	if (id0 != ks->chip->family_id) {
	dev_err(&ks->spi->dev, "chip family id mismatch: expected 0x%02x but 0x%02x read\n",
	ks->chip->family_id, id0);
	err = -ENODEV;
	goto err_out;
	}

	switch (ks->chip->family_id) {
	case FAMILY_KS8995:
	/* try reading chip id at CHIP ID1 */
	err = ks8995_read_reg(ks, KS8995_REG_ID1, &id1);
	if (err) {
	err = -EIO;
	goto err_out;
	}

	/* verify chip id */
	if ((get_chip_id(id1) == CHIPID_M) &&
	(get_chip_id(id1) == ks->chip->chip_id)) {
	/* KS8995MA */
	ks->revision_id = get_chip_rev(id1);
	} else if (get_chip_id(id1) != CHIPID_M) {
	/* KSZ8864RMN */
	err = ks8995_read_reg(ks, KS8995_REG_ID1, &ksz8864_id);
	if (err) {
	err = -EIO;
	goto err_out;
	}

	if ((ksz8864_id & 0x80) &&
	(ks->chip->chip_id == KSZ8864_CHIP_ID)) {
	ks->revision_id = get_chip_rev(id1);
	}

	} else {
	dev_err(&ks->spi->dev, "unsupported chip id for KS8995 family: 0x%02x\n",
	id1);
	err = -ENODEV;
	}
	break;
	case FAMILY_KSZ8795:
	/* try reading chip id at CHIP ID1 */
	err = ks8995_read_reg(ks, KS8995_REG_ID1, &id1);
	if (err) {
	err = -EIO;
	goto err_out;
	}

	if (get_chip_id(id1) == ks->chip->chip_id) {
	ks->revision_id = get_chip_rev(id1);
	} else {
	dev_err(&ks->spi->dev, "unsupported chip id for KSZ8795 family: 0x%02x\n",
	id1);
	err = -ENODEV;
	}
	break;
	default:
	dev_err(&ks->spi->dev, "unsupported family id: 0x%02x\n", id0);
	err = -ENODEV;
	break;
	}
	err_out:
	return err;
	}

	static const struct bin_attribute ks8995_registers_attr = {
	.attr = {
	.name = "registers",
	.mode = 0600,
	},
	.size = KS8995_REGS_SIZE,
	.read = ks8995_registers_read,
	.write = ks8995_registers_write,
	};

	/* ------------------------------------------------------------------------ */
	static int ks8995_probe(struct spi_device *spi)
	{
	struct ks8995_switch *ks;
	int err;
	int variant = spi_get_device_id(spi)->driver_data;

	if (variant >= max_variant) {
	dev_err(&spi->dev, "bad chip variant %d\n", variant);
	return -ENODEV;
	}

	ks = devm_kzalloc(&spi->dev, sizeof(*ks), GFP_KERNEL);
	if (!ks)
	return -ENOMEM;

	mutex_init(&ks->lock);
	ks->spi = spi;
	ks->chip = &ks8995_chip[variant];

	ks->reset_gpio = devm_gpiod_get_optional(&spi->dev, "reset",
	GPIOD_OUT_HIGH);
	err = PTR_ERR_OR_ZERO(ks->reset_gpio);
	if (err) {
	dev_err(&spi->dev,
	"failed to get reset gpio: %d\n", err);
	return err;
	}

	err = gpiod_set_consumer_name(ks->reset_gpio, "switch-reset");
	if (err)
	return err;

	/* de-assert switch reset */
	/* FIXME: this likely requires a delay */
	gpiod_set_value_cansleep(ks->reset_gpio, 0);

	spi_set_drvdata(spi, ks);

	spi->mode = SPI_MODE_0;
	spi->bits_per_word = 8;
	err = spi_setup(spi);
	if (err) {
	dev_err(&spi->dev, "spi_setup failed, err=%d\n", err);
	return err;
	}

	err = ks8995_get_revision(ks);
	if (err)
	return err;

	memcpy(&ks->regs_attr, &ks8995_registers_attr, sizeof(ks->regs_attr));
	ks->regs_attr.size = ks->chip->regs_size;

	err = ks8995_reset(ks);
	if (err)
	return err;

	sysfs_attr_init(&ks->regs_attr.attr);
	err = sysfs_create_bin_file(&spi->dev.kobj, &ks->regs_attr);
	if (err) {
	dev_err(&spi->dev, "unable to create sysfs file, err=%d\n",
	err);
	return err;
	}

	dev_info(&spi->dev, "%s device found, Chip ID:%x, Revision:%x\n",
	ks->chip->name, ks->chip->chip_id, ks->revision_id);

	return 0;
	}

	static void ks8995_remove(struct spi_device *spi)
	{
	struct ks8995_switch *ks = spi_get_drvdata(spi);

	sysfs_remove_bin_file(&spi->dev.kobj, &ks->regs_attr);

	/* assert reset */
	gpiod_set_value_cansleep(ks->reset_gpio, 1);
	}

	/* ------------------------------------------------------------------------ */
	static struct spi_driver ks8995_driver = {
	.driver = {
	.name = "spi-ks8995",
	.of_match_table = ks8895_spi_of_match,
	},
	.probe = ks8995_probe,
	.remove = ks8995_remove,
	.id_table = ks8995_id,
	};

	module_spi_driver(ks8995_driver);

	MODULE_DESCRIPTION(DRV_DESC);
	MODULE_VERSION(DRV_VERSION);
	MODULE_AUTHOR("Gabor Juhos <juhosg at openwrt.org>");
	MODULE_LICENSE("GPL v2");