mfd: Add Renesas Synchronization Management Unit (SMU) support

Add support for ClockMatrix(TM) and 82P33xxx families of timing
and synchronization devices. The access interface can be either
SPI or I2C. Currently, it will create 2 types of MFD devices,
which are to be used by the corresponding rsmu character device
driver and the PTP hardware clock driver, respectively.

Signed-off-by: Min Li <min.li.xe@renesas.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

1 files changed, 273 insertions, 0 deletions

diff --git a/drivers/mfd/rsmu_spi.c b/drivers/mfd/rsmu_spi.c
new file mode 100644
index 000000000000..fec2b4ec477c
--- /dev/null
+++ b/drivers/mfd/rsmu_spi.c
@@ -0,0 +1,273 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * SPI driver for Renesas Synchronization Management Unit (SMU) devices.
+ *
+ * Copyright (C) 2021 Integrated Device Technology, Inc., a Renesas Company.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/rsmu.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+#include <linux/spi/spi.h>
+
+#include "rsmu.h"
+
+#define	RSMU_CM_PAGE_ADDR		0x7C
+#define	RSMU_SABRE_PAGE_ADDR		0x7F
+#define	RSMU_HIGHER_ADDR_MASK		0xFF80
+#define	RSMU_HIGHER_ADDR_SHIFT		7
+#define	RSMU_LOWER_ADDR_MASK		0x7F
+
+static int rsmu_read_device(struct rsmu_ddata *rsmu, u8 reg, u8 *buf, u16 bytes)
+{
+	struct spi_device *client = to_spi_device(rsmu->dev);
+	struct spi_transfer xfer = {0};
+	struct spi_message msg;
+	u8 cmd[256] = {0};
+	u8 rsp[256] = {0};
+	int ret;
+
+	cmd[0] = reg | 0x80;
+	xfer.rx_buf = rsp;
+	xfer.len = bytes + 1;
+	xfer.tx_buf = cmd;
+	xfer.bits_per_word = client->bits_per_word;
+	xfer.speed_hz = client->max_speed_hz;
+
+	spi_message_init(&msg);
+	spi_message_add_tail(&xfer, &msg);
+
+	/*
+	 * 4-wire SPI is a shift register, so for every byte you send,
+	 * you get one back at the same time. Example read from 0xC024,
+	 * which has value of 0x2D
+	 *
+	 * MOSI:
+	 *       7C 00 C0 #Set page register
+	 *       A4 00    #MSB is set, so this is read command
+	 * MISO:
+	 *       XX 2D    #XX is a dummy byte from sending A4 and we
+	 *                 need to throw it away
+	 */
+	ret = spi_sync(client, &msg);
+	if (ret >= 0)
+		memcpy(buf, &rsp[1], xfer.len-1);
+
+	return ret;
+}
+
+static int rsmu_write_device(struct rsmu_ddata *rsmu, u8 reg, u8 *buf, u16 bytes)
+{
+	struct spi_device *client = to_spi_device(rsmu->dev);
+	struct spi_transfer xfer = {0};
+	struct spi_message msg;
+	u8 cmd[256] = {0};
+
+	cmd[0] = reg;
+	memcpy(&cmd[1], buf, bytes);
+
+	xfer.len = bytes + 1;
+	xfer.tx_buf = cmd;
+	xfer.bits_per_word = client->bits_per_word;
+	xfer.speed_hz = client->max_speed_hz;
+	spi_message_init(&msg);
+	spi_message_add_tail(&xfer, &msg);
+
+	return  spi_sync(client, &msg);
+}
+
+/*
+ * 1-byte (1B) offset addressing:
+ * 16-bit register address: the lower 7 bits of the register address come
+ * from the offset addr byte and the upper 9 bits come from the page register.
+ */
+static int rsmu_write_page_register(struct rsmu_ddata *rsmu, u16 reg)
+{
+	u8 page_reg;
+	u8 buf[2];
+	u16 bytes;
+	u16 page;
+	int err;
+
+	switch (rsmu->type) {
+	case RSMU_CM:
+		page_reg = RSMU_CM_PAGE_ADDR;
+		page = reg & RSMU_HIGHER_ADDR_MASK;
+		buf[0] = (u8)(page & 0xff);
+		buf[1] = (u8)((page >> 8) & 0xff);
+		bytes = 2;
+		break;
+	case RSMU_SABRE:
+		page_reg = RSMU_SABRE_PAGE_ADDR;
+		page = reg >> RSMU_HIGHER_ADDR_SHIFT;
+		buf[0] = (u8)(page & 0xff);
+		bytes = 1;
+		break;
+	default:
+		dev_err(rsmu->dev, "Unsupported RSMU device type: %d\n", rsmu->type);
+		return -ENODEV;
+	}
+
+	/* Simply return if we are on the same page */
+	if (rsmu->page == page)
+		return 0;
+
+	err = rsmu_write_device(rsmu, page_reg, buf, bytes);
+	if (err)
+		dev_err(rsmu->dev, "Failed to set page offset 0x%x\n", page);
+	else
+		/* Remember the last page */
+		rsmu->page = page;
+
+	return err;
+}
+
+static int rsmu_reg_read(void *context, unsigned int reg, unsigned int *val)
+{
+	struct rsmu_ddata *rsmu = spi_get_drvdata((struct spi_device *)context);
+	u8 addr = (u8)(reg & RSMU_LOWER_ADDR_MASK);
+	int err;
+
+	err = rsmu_write_page_register(rsmu, reg);
+	if (err)
+		return err;
+
+	err = rsmu_read_device(rsmu, addr, (u8 *)val, 1);
+	if (err)
+		dev_err(rsmu->dev, "Failed to read offset address 0x%x\n", addr);
+
+	return err;
+}
+
+static int rsmu_reg_write(void *context, unsigned int reg, unsigned int val)
+{
+	struct rsmu_ddata *rsmu = spi_get_drvdata((struct spi_device *)context);
+	u8 addr = (u8)(reg & RSMU_LOWER_ADDR_MASK);
+	u8 data = (u8)val;
+	int err;
+
+	err = rsmu_write_page_register(rsmu, reg);
+	if (err)
+		return err;
+
+	err = rsmu_write_device(rsmu, addr, &data, 1);
+	if (err)
+		dev_err(rsmu->dev,
+			"Failed to write offset address 0x%x\n", addr);
+
+	return err;
+}
+
+static const struct regmap_config rsmu_cm_regmap_config = {
+	.reg_bits = 16,
+	.val_bits = 8,
+	.max_register = 0xD000,
+	.reg_read = rsmu_reg_read,
+	.reg_write = rsmu_reg_write,
+	.cache_type = REGCACHE_NONE,
+};
+
+static const struct regmap_config rsmu_sabre_regmap_config = {
+	.reg_bits = 16,
+	.val_bits = 8,
+	.max_register = 0x400,
+	.reg_read = rsmu_reg_read,
+	.reg_write = rsmu_reg_write,
+	.cache_type = REGCACHE_NONE,
+};
+
+static int rsmu_spi_probe(struct spi_device *client)
+{
+	const struct spi_device_id *id = spi_get_device_id(client);
+	const struct regmap_config *cfg;
+	struct rsmu_ddata *rsmu;
+	int ret;
+
+	rsmu = devm_kzalloc(&client->dev, sizeof(*rsmu), GFP_KERNEL);
+	if (!rsmu)
+		return -ENOMEM;
+
+	spi_set_drvdata(client, rsmu);
+
+	rsmu->dev = &client->dev;
+	rsmu->type = (enum rsmu_type)id->driver_data;
+
+	/* Initialize regmap */
+	switch (rsmu->type) {
+	case RSMU_CM:
+		cfg = &rsmu_cm_regmap_config;
+		break;
+	case RSMU_SABRE:
+		cfg = &rsmu_sabre_regmap_config;
+		break;
+	default:
+		dev_err(rsmu->dev, "Unsupported RSMU device type: %d\n", rsmu->type);
+		return -ENODEV;
+	}
+
+	rsmu->regmap = devm_regmap_init(&client->dev, NULL, client, cfg);
+	if (IS_ERR(rsmu->regmap)) {
+		ret = PTR_ERR(rsmu->regmap);
+		dev_err(rsmu->dev, "Failed to allocate register map: %d\n", ret);
+		return ret;
+	}
+
+	return rsmu_core_init(rsmu);
+}
+
+static int rsmu_spi_remove(struct spi_device *client)
+{
+	struct rsmu_ddata *rsmu = spi_get_drvdata(client);
+
+	rsmu_core_exit(rsmu);
+
+	return 0;
+}
+
+static const struct spi_device_id rsmu_spi_id[] = {
+	{ "8a34000",  RSMU_CM },
+	{ "8a34001",  RSMU_CM },
+	{ "82p33810", RSMU_SABRE },
+	{ "82p33811", RSMU_SABRE },
+	{}
+};
+MODULE_DEVICE_TABLE(spi, rsmu_spi_id);
+
+static const struct of_device_id rsmu_spi_of_match[] = {
+	{ .compatible = "idt,8a34000",  .data = (void *)RSMU_CM },
+	{ .compatible = "idt,8a34001",  .data = (void *)RSMU_CM },
+	{ .compatible = "idt,82p33810", .data = (void *)RSMU_SABRE },
+	{ .compatible = "idt,82p33811", .data = (void *)RSMU_SABRE },
+	{}
+};
+MODULE_DEVICE_TABLE(of, rsmu_spi_of_match);
+
+static struct spi_driver rsmu_spi_driver = {
+	.driver = {
+		.name = "rsmu-spi",
+		.of_match_table = of_match_ptr(rsmu_spi_of_match),
+	},
+	.probe = rsmu_spi_probe,
+	.remove	= rsmu_spi_remove,
+	.id_table = rsmu_spi_id,
+};
+
+static int __init rsmu_spi_init(void)
+{
+	return spi_register_driver(&rsmu_spi_driver);
+}
+subsys_initcall(rsmu_spi_init);
+
+static void __exit rsmu_spi_exit(void)
+{
+	spi_unregister_driver(&rsmu_spi_driver);
+}
+module_exit(rsmu_spi_exit);
+
+MODULE_DESCRIPTION("Renesas SMU SPI driver");
+MODULE_LICENSE("GPL");