1 files changed, 316 insertions, 0 deletions
diff --git a/drivers/fsi/fsi-master-i2cr.c b/drivers/fsi/fsi-master-i2cr.c
new file mode 100644
index 000000000000..40f1f4d231e5
--- /dev/null
+++ b/drivers/fsi/fsi-master-i2cr.c
@@ -0,0 +1,316 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) IBM Corporation 2023 */
+
+#include <linux/device.h>
+#include <linux/fsi.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/mutex.h>
+
+#include "fsi-master-i2cr.h"
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/fsi_master_i2cr.h>
+
+#define I2CR_ADDRESS_CFAM(a)	((a) >> 2)
+#define I2CR_INITIAL_PARITY	true
+
+#define I2CR_STATUS_CMD		0x60002
+#define  I2CR_STATUS_ERR	 BIT_ULL(61)
+#define I2CR_ERROR_CMD		0x60004
+#define I2CR_LOG_CMD		0x60008
+
+static const u8 i2cr_cfam[] = {
+	0xc0, 0x02, 0x0d, 0xa6,
+	0x80, 0x01, 0x10, 0x02,
+	0x80, 0x01, 0x10, 0x02,
+	0x80, 0x01, 0x10, 0x02,
+	0x80, 0x01, 0x80, 0x52,
+	0x80, 0x01, 0x10, 0x02,
+	0x80, 0x01, 0x10, 0x02,
+	0x80, 0x01, 0x10, 0x02,
+	0x80, 0x01, 0x10, 0x02,
+	0x80, 0x01, 0x22, 0x2d,
+	0x00, 0x00, 0x00, 0x00,
+	0xde, 0xad, 0xc0, 0xde
+};
+
+static bool i2cr_check_parity32(u32 v, bool parity)
+{
+	u32 i;
+
+	for (i = 0; i < 32; ++i) {
+		if (v & (1u << i))
+			parity = !parity;
+	}
+
+	return parity;
+}
+
+static bool i2cr_check_parity64(u64 v)
+{
+	u32 i;
+	bool parity = I2CR_INITIAL_PARITY;
+
+	for (i = 0; i < 64; ++i) {
+		if (v & (1llu << i))
+			parity = !parity;
+	}
+
+	return parity;
+}
+
+static u32 i2cr_get_command(u32 address, bool parity)
+{
+	address <<= 1;
+
+	if (i2cr_check_parity32(address, parity))
+		address |= 1;
+
+	return address;
+}
+
+static int i2cr_transfer(struct i2c_client *client, u32 command, u64 *data)
+{
+	struct i2c_msg msgs[2];
+	int ret;
+
+	msgs[0].addr = client->addr;
+	msgs[0].flags = 0;
+	msgs[0].len = sizeof(command);
+	msgs[0].buf = (__u8 *)&command;
+	msgs[1].addr = client->addr;
+	msgs[1].flags = I2C_M_RD;
+	msgs[1].len = sizeof(*data);
+	msgs[1].buf = (__u8 *)data;
+
+	ret = i2c_transfer(client->adapter, msgs, 2);
+	if (ret == 2)
+		return 0;
+
+	trace_i2cr_i2c_error(client, command, ret);
+
+	if (ret < 0)
+		return ret;
+
+	return -EIO;
+}
+
+static int i2cr_check_status(struct i2c_client *client)
+{
+	u64 status;
+	int ret;
+
+	ret = i2cr_transfer(client, I2CR_STATUS_CMD, &status);
+	if (ret)
+		return ret;
+
+	if (status & I2CR_STATUS_ERR) {
+		u32 buf[3] = { 0, 0, 0 };
+		u64 error;
+		u64 log;
+
+		i2cr_transfer(client, I2CR_ERROR_CMD, &error);
+		i2cr_transfer(client, I2CR_LOG_CMD, &log);
+
+		trace_i2cr_status_error(client, status, error, log);
+
+		buf[0] = I2CR_STATUS_CMD;
+		i2c_master_send(client, (const char *)buf, sizeof(buf));
+
+		buf[0] = I2CR_ERROR_CMD;
+		i2c_master_send(client, (const char *)buf, sizeof(buf));
+
+		buf[0] = I2CR_LOG_CMD;
+		i2c_master_send(client, (const char *)buf, sizeof(buf));
+
+		dev_err(&client->dev, "status:%016llx error:%016llx log:%016llx\n", status, error,
+			log);
+		return -EREMOTEIO;
+	}
+
+	trace_i2cr_status(client, status);
+	return 0;
+}
+
+int fsi_master_i2cr_read(struct fsi_master_i2cr *i2cr, u32 addr, u64 *data)
+{
+	u32 command = i2cr_get_command(addr, I2CR_INITIAL_PARITY);
+	int ret;
+
+	mutex_lock(&i2cr->lock);
+
+	ret = i2cr_transfer(i2cr->client, command, data);
+	if (ret)
+		goto unlock;
+
+	ret = i2cr_check_status(i2cr->client);
+	if (ret)
+		goto unlock;
+
+	trace_i2cr_read(i2cr->client, command, data);
+
+unlock:
+	mutex_unlock(&i2cr->lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(fsi_master_i2cr_read);
+
+int fsi_master_i2cr_write(struct fsi_master_i2cr *i2cr, u32 addr, u64 data)
+{
+	u32 buf[3] = { 0 };
+	int ret;
+
+	buf[0] = i2cr_get_command(addr, i2cr_check_parity64(data));
+	memcpy(&buf[1], &data, sizeof(data));
+
+	mutex_lock(&i2cr->lock);
+
+	ret = i2c_master_send(i2cr->client, (const char *)buf, sizeof(buf));
+	if (ret == sizeof(buf)) {
+		ret = i2cr_check_status(i2cr->client);
+		if (!ret)
+			trace_i2cr_write(i2cr->client, buf[0], data);
+	} else {
+		trace_i2cr_i2c_error(i2cr->client, buf[0], ret);
+
+		if (ret >= 0)
+			ret = -EIO;
+	}
+
+	mutex_unlock(&i2cr->lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(fsi_master_i2cr_write);
+
+static int i2cr_read(struct fsi_master *master, int link, uint8_t id, uint32_t addr, void *val,
+		     size_t size)
+{
+	struct fsi_master_i2cr *i2cr = container_of(master, struct fsi_master_i2cr, master);
+	u64 data;
+	size_t i;
+	int ret;
+
+	if (link || id || (addr & 0xffff0000) || !(size == 1 || size == 2 || size == 4))
+		return -EINVAL;
+
+	/*
+	 * The I2CR doesn't have CFAM or FSI slave address space - only the
+	 * engines. In order for this to work with the FSI core, we need to
+	 * emulate at minimum the CFAM config table so that the appropriate
+	 * engines are discovered.
+	 */
+	if (addr < 0xc00) {
+		if (addr > sizeof(i2cr_cfam) - 4)
+			addr = (addr & 0x3) + (sizeof(i2cr_cfam) - 4);
+
+		memcpy(val, &i2cr_cfam[addr], size);
+		return 0;
+	}
+
+	ret = fsi_master_i2cr_read(i2cr, I2CR_ADDRESS_CFAM(addr), &data);
+	if (ret)
+		return ret;
+
+	/*
+	 * FSI core expects up to 4 bytes BE back, while I2CR replied with LE
+	 * bytes on the wire.
+	 */
+	for (i = 0; i < size; ++i)
+		((u8 *)val)[i] = ((u8 *)&data)[7 - i];
+
+	return 0;
+}
+
+static int i2cr_write(struct fsi_master *master, int link, uint8_t id, uint32_t addr,
+		      const void *val, size_t size)
+{
+	struct fsi_master_i2cr *i2cr = container_of(master, struct fsi_master_i2cr, master);
+	u64 data = 0;
+	size_t i;
+
+	if (link || id || (addr & 0xffff0000) || !(size == 1 || size == 2 || size == 4))
+		return -EINVAL;
+
+	/* I2CR writes to CFAM or FSI slave address are a successful no-op. */
+	if (addr < 0xc00)
+		return 0;
+
+	/*
+	 * FSI core passes up to 4 bytes BE, while the I2CR expects LE bytes on
+	 * the wire.
+	 */
+	for (i = 0; i < size; ++i)
+		((u8 *)&data)[7 - i] = ((u8 *)val)[i];
+
+	return fsi_master_i2cr_write(i2cr, I2CR_ADDRESS_CFAM(addr), data);
+}
+
+static void i2cr_release(struct device *dev)
+{
+	struct fsi_master_i2cr *i2cr = to_fsi_master_i2cr(to_fsi_master(dev));
+
+	of_node_put(dev->of_node);
+
+	kfree(i2cr);
+}
+
+static int i2cr_probe(struct i2c_client *client)
+{
+	struct fsi_master_i2cr *i2cr;
+	int ret;
+
+	i2cr = kzalloc(sizeof(*i2cr), GFP_KERNEL);
+	if (!i2cr)
+		return -ENOMEM;
+
+	/* Only one I2CR on any given I2C bus (fixed I2C device address) */
+	i2cr->master.idx = client->adapter->nr;
+	dev_set_name(&i2cr->master.dev, "i2cr%d", i2cr->master.idx);
+	i2cr->master.dev.parent = &client->dev;
+	i2cr->master.dev.of_node = of_node_get(dev_of_node(&client->dev));
+	i2cr->master.dev.release = i2cr_release;
+
+	i2cr->master.n_links = 1;
+	i2cr->master.read = i2cr_read;
+	i2cr->master.write = i2cr_write;
+
+	mutex_init(&i2cr->lock);
+	i2cr->client = client;
+
+	ret = fsi_master_register(&i2cr->master);
+	if (ret)
+		return ret;
+
+	i2c_set_clientdata(client, i2cr);
+	return 0;
+}
+
+static void i2cr_remove(struct i2c_client *client)
+{
+	struct fsi_master_i2cr *i2cr = i2c_get_clientdata(client);
+
+	fsi_master_unregister(&i2cr->master);
+}
+
+static const struct of_device_id i2cr_ids[] = {
+	{ .compatible = "ibm,i2cr-fsi-master" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, i2cr_ids);
+
+static struct i2c_driver i2cr_driver = {
+	.probe = i2cr_probe,
+	.remove = i2cr_remove,
+	.driver = {
+		.name = "fsi-master-i2cr",
+		.of_match_table = i2cr_ids,
+	},
+};
+
+module_i2c_driver(i2cr_driver)
+
+MODULE_AUTHOR("Eddie James <eajames@linux.ibm.com>");
+MODULE_DESCRIPTION("IBM I2C Responder virtual FSI master driver");
+MODULE_LICENSE("GPL");