i2c: Add drivers for the AMD PCIe MP2 I2C controller

MP2 controllers have two separate busses, so may accommodate up to two I2C
adapters. Those adapters are listed in the ACPI namespace with the
"AMDI0011" HID, and probed by a platform driver.

Communication with the MP2 takes place through MMIO registers, or through
DMA for more than 32 bytes transfers.

This is major rework of the patch submitted by Nehal-bakulchandra Shah from
AMD (https://patchwork.kernel.org/patch/10597369/).

Most of the event handling of v3 was rewritten to make it work with more
than one bus (e.g on Ryzen-based Lenovo Yoga 530), and this version
contains many other improvements.

Signed-off-by: Elie Morisse <syniurge@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

1 files changed, 367 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-amd-mp2-plat.c b/drivers/i2c/busses/i2c-amd-mp2-plat.c
new file mode 100644
index 000000000000..f5b3f00c6559
--- /dev/null
+++ b/drivers/i2c/busses/i2c-amd-mp2-plat.c
@@ -0,0 +1,367 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
+/*
+ * AMD MP2 platform driver
+ *
+ * Setup the I2C adapters enumerated in the ACPI namespace.
+ * MP2 controllers have 2 separate busses, up to 2 I2C adapters may be listed.
+ *
+ * Authors: Nehal Bakulchandra Shah <Nehal-bakulchandra.shah@amd.com>
+ *          Elie Morisse <syniurge@gmail.com>
+ */
+
+#include <linux/acpi.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#include "i2c-amd-mp2.h"
+
+#define AMD_MP2_I2C_MAX_RW_LENGTH ((1 << 12) - 1)
+#define AMD_I2C_TIMEOUT (msecs_to_jiffies(250))
+
+/**
+ * struct amd_i2c_dev - MP2 bus/i2c adapter context
+ * @common: shared context with the MP2 PCI driver
+ * @pdev: platform driver node
+ * @adap: i2c adapter
+ * @cmd_complete: xfer completion object
+ */
+struct amd_i2c_dev {
+	struct amd_i2c_common common;
+	struct platform_device *pdev;
+	struct i2c_adapter adap;
+	struct completion cmd_complete;
+};
+
+#define amd_i2c_dev_common(__common) \
+	container_of(__common, struct amd_i2c_dev, common)
+
+static int i2c_amd_dma_map(struct amd_i2c_common *i2c_common)
+{
+	struct device *dev_pci = &i2c_common->mp2_dev->pci_dev->dev;
+	struct amd_i2c_dev *i2c_dev = amd_i2c_dev_common(i2c_common);
+	enum dma_data_direction dma_direction =
+			i2c_common->msg->flags & I2C_M_RD ?
+			DMA_FROM_DEVICE : DMA_TO_DEVICE;
+
+	i2c_common->dma_buf = i2c_get_dma_safe_msg_buf(i2c_common->msg, 0);
+	i2c_common->dma_addr = dma_map_single(dev_pci, i2c_common->dma_buf,
+					      i2c_common->msg->len,
+					      dma_direction);
+
+	if (unlikely(dma_mapping_error(dev_pci, i2c_common->dma_addr))) {
+		dev_err(&i2c_dev->pdev->dev,
+			"Error while mapping dma buffer %p\n",
+			i2c_common->dma_buf);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static void i2c_amd_dma_unmap(struct amd_i2c_common *i2c_common)
+{
+	struct device *dev_pci = &i2c_common->mp2_dev->pci_dev->dev;
+	enum dma_data_direction dma_direction =
+			i2c_common->msg->flags & I2C_M_RD ?
+			DMA_FROM_DEVICE : DMA_TO_DEVICE;
+
+	dma_unmap_single(dev_pci, i2c_common->dma_addr,
+			 i2c_common->msg->len, dma_direction);
+
+	i2c_put_dma_safe_msg_buf(i2c_common->dma_buf, i2c_common->msg, true);
+}
+
+static void i2c_amd_start_cmd(struct amd_i2c_dev *i2c_dev)
+{
+	struct amd_i2c_common *i2c_common = &i2c_dev->common;
+
+	reinit_completion(&i2c_dev->cmd_complete);
+	i2c_common->cmd_success = false;
+}
+
+static void i2c_amd_cmd_completion(struct amd_i2c_common *i2c_common)
+{
+	struct amd_i2c_dev *i2c_dev = amd_i2c_dev_common(i2c_common);
+	union i2c_event *event = &i2c_common->eventval;
+
+	if (event->r.status == i2c_readcomplete_event)
+		dev_dbg(&i2c_dev->pdev->dev, "%s readdata:%*ph\n",
+			__func__, event->r.length,
+			i2c_common->msg->buf);
+
+	complete(&i2c_dev->cmd_complete);
+}
+
+static int i2c_amd_check_cmd_completion(struct amd_i2c_dev *i2c_dev)
+{
+	struct amd_i2c_common *i2c_common = &i2c_dev->common;
+	unsigned long timeout;
+
+	timeout = wait_for_completion_timeout(&i2c_dev->cmd_complete,
+					      i2c_dev->adap.timeout);
+
+	if ((i2c_common->reqcmd == i2c_read ||
+	     i2c_common->reqcmd == i2c_write) &&
+	    i2c_common->msg->len > 32)
+		i2c_amd_dma_unmap(i2c_common);
+
+	if (timeout == 0) {
+		amd_mp2_rw_timeout(i2c_common);
+		return -ETIMEDOUT;
+	}
+
+	amd_mp2_process_event(i2c_common);
+
+	if (!i2c_common->cmd_success)
+		return -EIO;
+
+	return 0;
+}
+
+static int i2c_amd_enable_set(struct amd_i2c_dev *i2c_dev, bool enable)
+{
+	struct amd_i2c_common *i2c_common = &i2c_dev->common;
+
+	i2c_amd_start_cmd(i2c_dev);
+	amd_mp2_bus_enable_set(i2c_common, enable);
+
+	return i2c_amd_check_cmd_completion(i2c_dev);
+}
+
+static int i2c_amd_xfer_msg(struct amd_i2c_dev *i2c_dev, struct i2c_msg *pmsg)
+{
+	struct amd_i2c_common *i2c_common = &i2c_dev->common;
+
+	i2c_amd_start_cmd(i2c_dev);
+	i2c_common->msg = pmsg;
+
+	if (pmsg->len > 32)
+		if (i2c_amd_dma_map(i2c_common))
+			return -EIO;
+
+	if (pmsg->flags & I2C_M_RD)
+		amd_mp2_rw(i2c_common, i2c_read);
+	else
+		amd_mp2_rw(i2c_common, i2c_write);
+
+	return i2c_amd_check_cmd_completion(i2c_dev);
+}
+
+static int i2c_amd_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
+{
+	struct amd_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
+	int i;
+	struct i2c_msg *pmsg;
+	int err;
+
+	/* the adapter might have been deleted while waiting for the bus lock */
+	if (unlikely(!i2c_dev->common.mp2_dev))
+		return -EINVAL;
+
+	amd_mp2_pm_runtime_get(i2c_dev->common.mp2_dev);
+
+	for (i = 0; i < num; i++) {
+		pmsg = &msgs[i];
+		err = i2c_amd_xfer_msg(i2c_dev, pmsg);
+		if (err)
+			break;
+	}
+
+	amd_mp2_pm_runtime_put(i2c_dev->common.mp2_dev);
+	return err ? err : num;
+}
+
+static u32 i2c_amd_func(struct i2c_adapter *a)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm i2c_amd_algorithm = {
+	.master_xfer = i2c_amd_xfer,
+	.functionality = i2c_amd_func,
+};
+
+#ifdef CONFIG_PM
+static int i2c_amd_suspend(struct amd_i2c_common *i2c_common)
+{
+	struct amd_i2c_dev *i2c_dev = amd_i2c_dev_common(i2c_common);
+
+	i2c_amd_enable_set(i2c_dev, false);
+	return 0;
+}
+
+static int i2c_amd_resume(struct amd_i2c_common *i2c_common)
+{
+	struct amd_i2c_dev *i2c_dev = amd_i2c_dev_common(i2c_common);
+
+	return i2c_amd_enable_set(i2c_dev, true);
+}
+#endif
+
+static enum speed_enum i2c_amd_get_bus_speed(struct platform_device *pdev)
+{
+	u32 acpi_speed;
+	int i;
+	static const u32 supported_speeds[] = {
+		0, 100000, 400000, 1000000, 1400000, 3400000
+	};
+
+	acpi_speed = i2c_acpi_find_bus_speed(&pdev->dev);
+	/* round down to the lowest standard speed */
+	for (i = 1; i < ARRAY_SIZE(supported_speeds); i++) {
+		if (acpi_speed < supported_speeds[i])
+			break;
+	}
+	acpi_speed = supported_speeds[i - 1];
+
+	switch (acpi_speed) {
+	case 100000:
+		return speed100k;
+	case 400000:
+		return speed400k;
+	case 1000000:
+		return speed1000k;
+	case 1400000:
+		return speed1400k;
+	case 3400000:
+		return speed3400k;
+	default:
+		return speed400k;
+	}
+}
+
+static const struct i2c_adapter_quirks amd_i2c_dev_quirks = {
+	.max_read_len = AMD_MP2_I2C_MAX_RW_LENGTH,
+	.max_write_len = AMD_MP2_I2C_MAX_RW_LENGTH,
+};
+
+static int i2c_amd_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct amd_i2c_dev *i2c_dev;
+	acpi_handle handle = ACPI_HANDLE(&pdev->dev);
+	struct acpi_device *adev;
+	struct amd_mp2_dev *mp2_dev;
+	const char *uid;
+
+	if (acpi_bus_get_device(handle, &adev))
+		return -ENODEV;
+
+	/* The ACPI namespace doesn't contain information about which MP2 PCI
+	 * device an AMDI0011 ACPI device is related to, so assume that there's
+	 * only one MP2 PCI device per system.
+	 */
+	mp2_dev = amd_mp2_find_device();
+	if (!mp2_dev || !mp2_dev->probed)
+		/* The MP2 PCI device should get probed later */
+		return -EPROBE_DEFER;
+
+	i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL);
+	if (!i2c_dev)
+		return -ENOMEM;
+
+	i2c_dev->common.mp2_dev = mp2_dev;
+	i2c_dev->pdev = pdev;
+	platform_set_drvdata(pdev, i2c_dev);
+
+	i2c_dev->common.cmd_completion = &i2c_amd_cmd_completion;
+#ifdef CONFIG_PM
+	i2c_dev->common.suspend = &i2c_amd_suspend;
+	i2c_dev->common.resume = &i2c_amd_resume;
+#endif
+
+	uid = adev->pnp.unique_id;
+	if (!uid) {
+		dev_err(&pdev->dev, "missing UID/bus id!\n");
+		return -EINVAL;
+	} else if (strcmp(uid, "0") == 0) {
+		i2c_dev->common.bus_id = 0;
+	} else if (strcmp(uid, "1") == 0) {
+		i2c_dev->common.bus_id = 1;
+	} else {
+		dev_err(&pdev->dev, "incorrect UID/bus id \"%s\"!\n", uid);
+		return -EINVAL;
+	}
+	dev_dbg(&pdev->dev, "bus id is %u\n", i2c_dev->common.bus_id);
+
+	/* Register the adapter */
+	amd_mp2_pm_runtime_get(mp2_dev);
+
+	i2c_dev->common.reqcmd = i2c_none;
+	if (amd_mp2_register_cb(&i2c_dev->common))
+		return -EINVAL;
+	device_link_add(&i2c_dev->pdev->dev, &mp2_dev->pci_dev->dev,
+			DL_FLAG_AUTOREMOVE_CONSUMER);
+
+	i2c_dev->common.i2c_speed = i2c_amd_get_bus_speed(pdev);
+
+	/* Setup i2c adapter description */
+	i2c_dev->adap.owner = THIS_MODULE;
+	i2c_dev->adap.algo = &i2c_amd_algorithm;
+	i2c_dev->adap.quirks = &amd_i2c_dev_quirks;
+	i2c_dev->adap.dev.parent = &pdev->dev;
+	i2c_dev->adap.algo_data = i2c_dev;
+	i2c_dev->adap.timeout = AMD_I2C_TIMEOUT;
+	ACPI_COMPANION_SET(&i2c_dev->adap.dev, ACPI_COMPANION(&pdev->dev));
+	i2c_dev->adap.dev.of_node = pdev->dev.of_node;
+	snprintf(i2c_dev->adap.name, sizeof(i2c_dev->adap.name),
+		 "AMD MP2 i2c bus %u", i2c_dev->common.bus_id);
+	i2c_set_adapdata(&i2c_dev->adap, i2c_dev);
+
+	init_completion(&i2c_dev->cmd_complete);
+
+	/* Enable the bus */
+	if (i2c_amd_enable_set(i2c_dev, true))
+		dev_err(&pdev->dev, "initial bus enable failed\n");
+
+	/* Attach to the i2c layer */
+	ret = i2c_add_adapter(&i2c_dev->adap);
+
+	amd_mp2_pm_runtime_put(mp2_dev);
+
+	if (ret < 0)
+		dev_err(&pdev->dev, "i2c add adapter failed = %d\n", ret);
+
+	return ret;
+}
+
+static int i2c_amd_remove(struct platform_device *pdev)
+{
+	struct amd_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
+	struct amd_i2c_common *i2c_common = &i2c_dev->common;
+
+	i2c_lock_bus(&i2c_dev->adap, I2C_LOCK_ROOT_ADAPTER);
+
+	i2c_amd_enable_set(i2c_dev, false);
+	amd_mp2_unregister_cb(i2c_common);
+	i2c_common->mp2_dev = NULL;
+
+	i2c_unlock_bus(&i2c_dev->adap, I2C_LOCK_ROOT_ADAPTER);
+
+	i2c_del_adapter(&i2c_dev->adap);
+	return 0;
+}
+
+static const struct acpi_device_id i2c_amd_acpi_match[] = {
+	{ "AMDI0011" },
+	{ },
+};
+MODULE_DEVICE_TABLE(acpi, i2c_amd_acpi_match);
+
+static struct platform_driver i2c_amd_plat_driver = {
+	.probe = i2c_amd_probe,
+	.remove = i2c_amd_remove,
+	.driver = {
+		.name = "i2c_amd_mp2",
+		.acpi_match_table = ACPI_PTR(i2c_amd_acpi_match),
+	},
+};
+module_platform_driver(i2c_amd_plat_driver);
+
+MODULE_DESCRIPTION("AMD(R) MP2 I2C Platform Driver");
+MODULE_AUTHOR("Nehal Shah <nehal-bakulchandra.shah@amd.com>");
+MODULE_AUTHOR("Elie Morisse <syniurge@gmail.com>");
+MODULE_LICENSE("Dual BSD/GPL");