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, 483 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-amd-mp2-pci.c b/drivers/i2c/busses/i2c-amd-mp2-pci.c
new file mode 100644
index 000000000000..455e1f36a2a3
--- /dev/null
+++ b/drivers/i2c/busses/i2c-amd-mp2-pci.c
@@ -0,0 +1,483 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
+/*
+ * AMD MP2 PCIe communication driver
+ *
+ * Authors: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
+ *          Elie Morisse <syniurge@gmail.com>
+ */
+
+#include <linux/dma-mapping.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/slab.h>
+
+#include "i2c-amd-mp2.h"
+
+#include <linux/io-64-nonatomic-lo-hi.h>
+
+static void amd_mp2_c2p_mutex_lock(struct amd_i2c_common *i2c_common)
+{
+	struct amd_mp2_dev *privdata = i2c_common->mp2_dev;
+
+	/* there is only one data mailbox for two i2c adapters */
+	mutex_lock(&privdata->c2p_lock);
+	privdata->c2p_lock_busid = i2c_common->bus_id;
+}
+
+static void amd_mp2_c2p_mutex_unlock(struct amd_i2c_common *i2c_common)
+{
+	struct amd_mp2_dev *privdata = i2c_common->mp2_dev;
+
+	if (unlikely(privdata->c2p_lock_busid != i2c_common->bus_id)) {
+		dev_warn(ndev_dev(privdata),
+			 "bus %d attempting to unlock C2P locked by bus %d\n",
+			 i2c_common->bus_id, privdata->c2p_lock_busid);
+		return;
+	}
+
+	mutex_unlock(&privdata->c2p_lock);
+}
+
+static int amd_mp2_cmd(struct amd_i2c_common *i2c_common,
+		       union i2c_cmd_base i2c_cmd_base)
+{
+	struct amd_mp2_dev *privdata = i2c_common->mp2_dev;
+	void __iomem *reg;
+
+	i2c_common->reqcmd = i2c_cmd_base.s.i2c_cmd;
+
+	reg = privdata->mmio + ((i2c_cmd_base.s.bus_id == 1) ?
+				AMD_C2P_MSG1 : AMD_C2P_MSG0);
+	writel(i2c_cmd_base.ul, reg);
+
+	return 0;
+}
+
+int amd_mp2_bus_enable_set(struct amd_i2c_common *i2c_common, bool enable)
+{
+	struct amd_mp2_dev *privdata = i2c_common->mp2_dev;
+	union i2c_cmd_base i2c_cmd_base;
+
+	dev_dbg(ndev_dev(privdata), "%s id: %d\n", __func__,
+		i2c_common->bus_id);
+
+	i2c_cmd_base.ul = 0;
+	i2c_cmd_base.s.i2c_cmd = enable ? i2c_enable : i2c_disable;
+	i2c_cmd_base.s.bus_id = i2c_common->bus_id;
+	i2c_cmd_base.s.i2c_speed = i2c_common->i2c_speed;
+
+	amd_mp2_c2p_mutex_lock(i2c_common);
+
+	return amd_mp2_cmd(i2c_common, i2c_cmd_base);
+}
+EXPORT_SYMBOL_GPL(amd_mp2_bus_enable_set);
+
+static void amd_mp2_cmd_rw_fill(struct amd_i2c_common *i2c_common,
+				union i2c_cmd_base *i2c_cmd_base,
+				enum i2c_cmd reqcmd)
+{
+	i2c_cmd_base->s.i2c_cmd = reqcmd;
+	i2c_cmd_base->s.bus_id = i2c_common->bus_id;
+	i2c_cmd_base->s.i2c_speed = i2c_common->i2c_speed;
+	i2c_cmd_base->s.slave_addr = i2c_common->msg->addr;
+	i2c_cmd_base->s.length = i2c_common->msg->len;
+}
+
+int amd_mp2_rw(struct amd_i2c_common *i2c_common, enum i2c_cmd reqcmd)
+{
+	struct amd_mp2_dev *privdata = i2c_common->mp2_dev;
+	union i2c_cmd_base i2c_cmd_base;
+
+	amd_mp2_cmd_rw_fill(i2c_common, &i2c_cmd_base, reqcmd);
+	amd_mp2_c2p_mutex_lock(i2c_common);
+
+	if (i2c_common->msg->len <= 32) {
+		i2c_cmd_base.s.mem_type = use_c2pmsg;
+		if (reqcmd == i2c_write)
+			memcpy_toio(privdata->mmio + AMD_C2P_MSG2,
+				    i2c_common->msg->buf,
+				    i2c_common->msg->len);
+	} else {
+		i2c_cmd_base.s.mem_type = use_dram;
+		writeq((u64)i2c_common->dma_addr,
+		       privdata->mmio + AMD_C2P_MSG2);
+	}
+
+	return amd_mp2_cmd(i2c_common, i2c_cmd_base);
+}
+EXPORT_SYMBOL_GPL(amd_mp2_rw);
+
+static void amd_mp2_pci_check_rw_event(struct amd_i2c_common *i2c_common)
+{
+	struct amd_mp2_dev *privdata = i2c_common->mp2_dev;
+	int len = i2c_common->eventval.r.length;
+	u32 slave_addr = i2c_common->eventval.r.slave_addr;
+	bool err = false;
+
+	if (unlikely(len != i2c_common->msg->len)) {
+		dev_err(ndev_dev(privdata),
+			"length %d in event doesn't match buffer length %d!\n",
+			len, i2c_common->msg->len);
+		err = true;
+	}
+
+	if (unlikely(slave_addr != i2c_common->msg->addr)) {
+		dev_err(ndev_dev(privdata),
+			"unexpected slave address %x (expected: %x)!\n",
+			slave_addr, i2c_common->msg->addr);
+		err = true;
+	}
+
+	if (!err)
+		i2c_common->cmd_success = true;
+}
+
+static void __amd_mp2_process_event(struct amd_i2c_common *i2c_common)
+{
+	struct amd_mp2_dev *privdata = i2c_common->mp2_dev;
+	enum status_type sts = i2c_common->eventval.r.status;
+	enum response_type res = i2c_common->eventval.r.response;
+	int len = i2c_common->eventval.r.length;
+
+	if (res != command_success) {
+		if (res != command_failed)
+			dev_err(ndev_dev(privdata), "invalid response to i2c command!\n");
+		return;
+	}
+
+	switch (i2c_common->reqcmd) {
+	case i2c_read:
+		if (sts == i2c_readcomplete_event) {
+			amd_mp2_pci_check_rw_event(i2c_common);
+			if (len <= 32)
+				memcpy_fromio(i2c_common->msg->buf,
+					      privdata->mmio + AMD_C2P_MSG2,
+					      len);
+		} else if (sts != i2c_readfail_event) {
+			dev_err(ndev_dev(privdata),
+				"invalid i2c status after read (%d)!\n", sts);
+		}
+		break;
+	case i2c_write:
+		if (sts == i2c_writecomplete_event)
+			amd_mp2_pci_check_rw_event(i2c_common);
+		else if (sts != i2c_writefail_event)
+			dev_err(ndev_dev(privdata),
+				"invalid i2c status after write (%d)!\n", sts);
+		break;
+	case i2c_enable:
+		if (sts == i2c_busenable_complete)
+			i2c_common->cmd_success = true;
+		else if (sts != i2c_busenable_failed)
+			dev_err(ndev_dev(privdata),
+				"invalid i2c status after bus enable (%d)!\n",
+				sts);
+		break;
+	case i2c_disable:
+		if (sts == i2c_busdisable_complete)
+			i2c_common->cmd_success = true;
+		else if (sts != i2c_busdisable_failed)
+			dev_err(ndev_dev(privdata),
+				"invalid i2c status after bus disable (%d)!\n",
+				sts);
+		break;
+	default:
+		break;
+	}
+}
+
+void amd_mp2_process_event(struct amd_i2c_common *i2c_common)
+{
+	struct amd_mp2_dev *privdata = i2c_common->mp2_dev;
+
+	if (unlikely(i2c_common->reqcmd == i2c_none)) {
+		dev_warn(ndev_dev(privdata),
+			 "received msg but no cmd was sent (bus = %d)!\n",
+			 i2c_common->bus_id);
+		return;
+	}
+
+	__amd_mp2_process_event(i2c_common);
+
+	i2c_common->reqcmd = i2c_none;
+	amd_mp2_c2p_mutex_unlock(i2c_common);
+}
+EXPORT_SYMBOL_GPL(amd_mp2_process_event);
+
+static irqreturn_t amd_mp2_irq_isr(int irq, void *dev)
+{
+	struct amd_mp2_dev *privdata = dev;
+	struct amd_i2c_common *i2c_common;
+	u32 val;
+	unsigned int bus_id;
+	void __iomem *reg;
+	enum irqreturn ret = IRQ_NONE;
+
+	for (bus_id = 0; bus_id < 2; bus_id++) {
+		i2c_common = privdata->busses[bus_id];
+		if (!i2c_common)
+			continue;
+
+		reg = privdata->mmio + ((bus_id == 0) ?
+					AMD_P2C_MSG1 : AMD_P2C_MSG2);
+		val = readl(reg);
+		if (val != 0) {
+			writel(0, reg);
+			writel(0, privdata->mmio + AMD_P2C_MSG_INTEN);
+			i2c_common->eventval.ul = val;
+			i2c_common->cmd_completion(i2c_common);
+
+			ret = IRQ_HANDLED;
+		}
+	}
+
+	if (ret != IRQ_HANDLED) {
+		val = readl(privdata->mmio + AMD_P2C_MSG_INTEN);
+		if (val != 0) {
+			writel(0, privdata->mmio + AMD_P2C_MSG_INTEN);
+			dev_warn(ndev_dev(privdata),
+				 "received irq without message\n");
+			ret = IRQ_HANDLED;
+		}
+	}
+
+	return ret;
+}
+
+void amd_mp2_rw_timeout(struct amd_i2c_common *i2c_common)
+{
+	i2c_common->reqcmd = i2c_none;
+	amd_mp2_c2p_mutex_unlock(i2c_common);
+}
+EXPORT_SYMBOL_GPL(amd_mp2_rw_timeout);
+
+int amd_mp2_register_cb(struct amd_i2c_common *i2c_common)
+{
+	struct amd_mp2_dev *privdata = i2c_common->mp2_dev;
+
+	if (i2c_common->bus_id > 1)
+		return -EINVAL;
+
+	if (privdata->busses[i2c_common->bus_id]) {
+		dev_err(ndev_dev(privdata),
+			"Bus %d already taken!\n", i2c_common->bus_id);
+		return -EINVAL;
+	}
+
+	privdata->busses[i2c_common->bus_id] = i2c_common;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(amd_mp2_register_cb);
+
+int amd_mp2_unregister_cb(struct amd_i2c_common *i2c_common)
+{
+	struct amd_mp2_dev *privdata = i2c_common->mp2_dev;
+
+	privdata->busses[i2c_common->bus_id] = NULL;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(amd_mp2_unregister_cb);
+
+static void amd_mp2_clear_reg(struct amd_mp2_dev *privdata)
+{
+	int reg;
+
+	for (reg = AMD_C2P_MSG0; reg <= AMD_C2P_MSG9; reg += 4)
+		writel(0, privdata->mmio + reg);
+
+	for (reg = AMD_P2C_MSG1; reg <= AMD_P2C_MSG2; reg += 4)
+		writel(0, privdata->mmio + reg);
+}
+
+static int amd_mp2_pci_init(struct amd_mp2_dev *privdata,
+			    struct pci_dev *pci_dev)
+{
+	int rc;
+
+	pci_set_drvdata(pci_dev, privdata);
+
+	rc = pcim_enable_device(pci_dev);
+	if (rc) {
+		dev_err(ndev_dev(privdata), "Failed to enable MP2 PCI device\n");
+		goto err_pci_enable;
+	}
+
+	rc = pcim_iomap_regions(pci_dev, 1 << 2, pci_name(pci_dev));
+	if (rc) {
+		dev_err(ndev_dev(privdata), "I/O memory remapping failed\n");
+		goto err_pci_enable;
+	}
+	privdata->mmio = pcim_iomap_table(pci_dev)[2];
+
+	pci_set_master(pci_dev);
+
+	rc = pci_set_dma_mask(pci_dev, DMA_BIT_MASK(64));
+	if (rc) {
+		rc = pci_set_dma_mask(pci_dev, DMA_BIT_MASK(32));
+		if (rc)
+			goto err_dma_mask;
+	}
+
+	/* Set up intx irq */
+	writel(0, privdata->mmio + AMD_P2C_MSG_INTEN);
+	pci_intx(pci_dev, 1);
+	rc = devm_request_irq(&pci_dev->dev, pci_dev->irq, amd_mp2_irq_isr,
+			      IRQF_SHARED, dev_name(&pci_dev->dev), privdata);
+	if (rc)
+		dev_err(&pci_dev->dev, "Failure requesting irq %i: %d\n",
+			pci_dev->irq, rc);
+
+	return rc;
+
+err_dma_mask:
+	pci_clear_master(pci_dev);
+err_pci_enable:
+	pci_set_drvdata(pci_dev, NULL);
+	return rc;
+}
+
+static int amd_mp2_pci_probe(struct pci_dev *pci_dev,
+			     const struct pci_device_id *id)
+{
+	struct amd_mp2_dev *privdata;
+	int rc;
+
+	privdata = devm_kzalloc(&pci_dev->dev, sizeof(*privdata), GFP_KERNEL);
+	if (!privdata)
+		return -ENOMEM;
+
+	rc = amd_mp2_pci_init(privdata, pci_dev);
+	if (rc)
+		return rc;
+
+	mutex_init(&privdata->c2p_lock);
+	privdata->pci_dev = pci_dev;
+
+	pm_runtime_set_autosuspend_delay(&pci_dev->dev, 1000);
+	pm_runtime_use_autosuspend(&pci_dev->dev);
+	pm_runtime_put_autosuspend(&pci_dev->dev);
+	pm_runtime_allow(&pci_dev->dev);
+
+	privdata->probed = true;
+
+	dev_info(&pci_dev->dev, "MP2 device registered.\n");
+	return 0;
+}
+
+static void amd_mp2_pci_remove(struct pci_dev *pci_dev)
+{
+	struct amd_mp2_dev *privdata = pci_get_drvdata(pci_dev);
+
+	pm_runtime_forbid(&pci_dev->dev);
+	pm_runtime_get_noresume(&pci_dev->dev);
+
+	pci_intx(pci_dev, 0);
+	pci_clear_master(pci_dev);
+
+	amd_mp2_clear_reg(privdata);
+}
+
+#ifdef CONFIG_PM
+static int amd_mp2_pci_suspend(struct device *dev)
+{
+	struct pci_dev *pci_dev = to_pci_dev(dev);
+	struct amd_mp2_dev *privdata = pci_get_drvdata(pci_dev);
+	struct amd_i2c_common *i2c_common;
+	unsigned int bus_id;
+	int ret = 0;
+
+	for (bus_id = 0; bus_id < 2; bus_id++) {
+		i2c_common = privdata->busses[bus_id];
+		if (i2c_common)
+			i2c_common->suspend(i2c_common);
+	}
+
+	ret = pci_save_state(pci_dev);
+	if (ret) {
+		dev_err(ndev_dev(privdata),
+			"pci_save_state failed = %d\n", ret);
+		return ret;
+	}
+
+	pci_disable_device(pci_dev);
+	return ret;
+}
+
+static int amd_mp2_pci_resume(struct device *dev)
+{
+	struct pci_dev *pci_dev = to_pci_dev(dev);
+	struct amd_mp2_dev *privdata = pci_get_drvdata(pci_dev);
+	struct amd_i2c_common *i2c_common;
+	unsigned int bus_id;
+	int ret = 0;
+
+	pci_restore_state(pci_dev);
+	ret = pci_enable_device(pci_dev);
+	if (ret < 0) {
+		dev_err(ndev_dev(privdata),
+			"pci_enable_device failed = %d\n", ret);
+		return ret;
+	}
+
+	for (bus_id = 0; bus_id < 2; bus_id++) {
+		i2c_common = privdata->busses[bus_id];
+		if (i2c_common) {
+			ret = i2c_common->resume(i2c_common);
+			if (ret < 0)
+				return ret;
+		}
+	}
+
+	return ret;
+}
+
+static UNIVERSAL_DEV_PM_OPS(amd_mp2_pci_pm_ops, amd_mp2_pci_suspend,
+			    amd_mp2_pci_resume, NULL);
+#endif /* CONFIG_PM */
+
+static const struct pci_device_id amd_mp2_pci_tbl[] = {
+	{PCI_VDEVICE(AMD, PCI_DEVICE_ID_AMD_MP2)},
+	{0}
+};
+MODULE_DEVICE_TABLE(pci, amd_mp2_pci_tbl);
+
+static struct pci_driver amd_mp2_pci_driver = {
+	.name		= "i2c_amd_mp2",
+	.id_table	= amd_mp2_pci_tbl,
+	.probe		= amd_mp2_pci_probe,
+	.remove		= amd_mp2_pci_remove,
+#ifdef CONFIG_PM
+	.driver = {
+		.pm	= &amd_mp2_pci_pm_ops,
+	},
+#endif
+};
+module_pci_driver(amd_mp2_pci_driver);
+
+static int amd_mp2_device_match(struct device *dev, void *data)
+{
+	return 1;
+}
+
+struct amd_mp2_dev *amd_mp2_find_device(void)
+{
+	struct device *dev;
+	struct pci_dev *pci_dev;
+
+	dev = driver_find_device(&amd_mp2_pci_driver.driver, NULL, NULL,
+				 amd_mp2_device_match);
+	if (!dev)
+		return NULL;
+
+	pci_dev = to_pci_dev(dev);
+	return (struct amd_mp2_dev *)pci_get_drvdata(pci_dev);
+}
+EXPORT_SYMBOL_GPL(amd_mp2_find_device);
+
+MODULE_DESCRIPTION("AMD(R) PCI-E MP2 I2C Controller Driver");
+MODULE_AUTHOR("Shyam Sundar S K <Shyam-sundar.S-k@amd.com>");
+MODULE_AUTHOR("Elie Morisse <syniurge@gmail.com>");
+MODULE_LICENSE("Dual BSD/GPL");