Date:   Tue, 30 Mar 2021 12:17:15 +0530
From:   Sanket Goswami <Sanket.Goswami@....com>
To:     jarkko.nikula@...ux.intel.com, andriy.shevchenko@...ux.intel.com,
        mika.westerberg@...ux.intel.com
Cc:     linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        Sanket Goswami <Sanket.Goswami@....com>,
        Shyam Sundar S K <Shyam-sundar.S-k@....com>,
        Nehal Bakulchandra Shah <Nehal-Bakulchandra.shah@....com>
Subject: [PATCH v3] i2c: designware: Add driver support for AMD NAVI GPU

The Latest AMD NAVI GPU card has an integrated Type-C controller and
Designware I2C with PCI Interface. The Type-C controller can be
accessed over I2C. The client driver is part of the USB Type-C UCSI
driver.

Also, there exists a couple of notable IP limitations that are dealt as
workarounds:
- I2C transaction work on a polling mode as IP does not generate
interrupt.
- I2C read command sent twice to address the IP issues.
- AMD NAVI GPU based products are already in the commercial market,
  hence some of the I2C parameters are statically programmed as it can
  not be part of ACPI table.

Reviewed-by: Shyam Sundar S K <Shyam-sundar.S-k@....com>
Co-developed-by: Nehal Bakulchandra Shah <Nehal-Bakulchandra.shah@....com>
Signed-off-by: Nehal Bakulchandra Shah <Nehal-Bakulchandra.shah@....com>
Signed-off-by: Sanket Goswami <Sanket.Goswami@....com>
---
Changes in v3:
- Fixes runtime PM issue.
- Addressed review comments were given by Jarkko and Andy.

Changes in v2:
- Utilized existing functionality of i2c_dw_xfer_init to configure I2C
  bus.
- Removed i2c_dw_populate_client and rewrrient navi_amd_register_client
  to deduplicate from existing drivers.
- Addressed review comments were given by Andy.

 drivers/i2c/busses/i2c-designware-common.c |   3 +
 drivers/i2c/busses/i2c-designware-core.h   |   3 +
 drivers/i2c/busses/i2c-designware-master.c | 151 +++++++++++++++++++++
 drivers/i2c/busses/i2c-designware-pcidrv.c |  57 ++++++++
 4 files changed, 214 insertions(+)

diff --git a/drivers/i2c/busses/i2c-designware-common.c b/drivers/i2c/busses/i2c-designware-common.c
index 3c19aada4b30..d14ab2d2f23b 100644
--- a/drivers/i2c/busses/i2c-designware-common.c
+++ b/drivers/i2c/busses/i2c-designware-common.c
@@ -150,6 +150,9 @@ int i2c_dw_init_regmap(struct dw_i2c_dev *dev)
 	reg = readl(dev->base + DW_IC_COMP_TYPE);
 	i2c_dw_release_lock(dev);
 
+	if (dev->flags & MODEL_AMD_NAVI_GPU)
+		map_cfg.max_register = AMD_UCSI_INTR_REG;
+
 	if (reg == swab32(DW_IC_COMP_TYPE_VALUE)) {
 		map_cfg.reg_read = dw_reg_read_swab;
 		map_cfg.reg_write = dw_reg_write_swab;
diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index 5392b82f68a4..f65a15bac862 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -293,9 +293,12 @@ struct dw_i2c_dev {
 #define ACCESS_INTR_MASK	BIT(0)
 #define ACCESS_NO_IRQ_SUSPEND	BIT(1)
 
+#define MODEL_AMD_NAVI_GPU	BIT(2)
 #define MODEL_MSCC_OCELOT	BIT(8)
 #define MODEL_BAIKAL_BT1	BIT(9)
 #define MODEL_MASK		GENMASK(11, 8)
+#define AMD_UCSI_INTR_EN	0xd
+#define AMD_UCSI_INTR_REG	0x474
 
 int i2c_dw_init_regmap(struct dw_i2c_dev *dev);
 u32 i2c_dw_scl_hcnt(u32 ic_clk, u32 tSYMBOL, u32 tf, int cond, int offset);
diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c
index dd27b9dbe931..60d9eae9df51 100644
--- a/drivers/i2c/busses/i2c-designware-master.c
+++ b/drivers/i2c/busses/i2c-designware-master.c
@@ -23,6 +23,10 @@
 
 #include "i2c-designware-core.h"
 
+#define AMD_TIMEOUT_MIN_MSEC	10000
+#define AMD_TIMEOUT_MAX_MSEC	11000
+#define AMD_MASTERCFG_MASK	GENMASK(15, 0)
+
 static void i2c_dw_configure_fifo_master(struct dw_i2c_dev *dev)
 {
 	/* Configure Tx/Rx FIFO threshold levels */
@@ -259,6 +263,127 @@ static void i2c_dw_xfer_init(struct dw_i2c_dev *dev)
 	regmap_write(dev->map, DW_IC_INTR_MASK, DW_IC_INTR_MASTER_MASK);
 }
 
+static int i2c_dw_check_stopbit(struct dw_i2c_dev *dev)
+{
+	u32 val;
+	int ret;
+
+	ret = regmap_read_poll_timeout(dev->map, DW_IC_INTR_STAT, val,
+				       !(val & DW_IC_INTR_STOP_DET),
+					1100, 20000);
+	if (ret) {
+		dev_err(dev->dev, "i2c timeout error %d\n", ret);
+		return -ETIMEDOUT;
+	}
+
+	regmap_read(dev->map, DW_IC_CLR_INTR, &val);
+	if (val & DW_IC_INTR_STOP_DET)
+		return -ETIMEDOUT;
+
+	return 0;
+}
+
+static int i2c_dw_status(struct dw_i2c_dev *dev)
+{
+	int status;
+
+	status = i2c_dw_wait_bus_not_busy(dev);
+	if (status)
+		return -ETIMEDOUT;
+
+	return i2c_dw_check_stopbit(dev);
+}
+
+/*
+ * Initiate and continue master read/write transaction with polling
+ * based transfer routine afterward write messages into the tx buffer.
+ */
+static int amd_i2c_dw_xfer_quirk(struct i2c_adapter *adap, struct i2c_msg *msgs, int num_msgs)
+{
+	struct dw_i2c_dev *dev = i2c_get_adapdata(adap);
+	int msg_wrt_idx, msg_itr_lmt, buf_len, data_idx;
+	int cmd = 0, ret, status;
+	u8 *tx_buf;
+	u32 val;
+	/*
+	 * In order to enable the interrupt for UCSI i.e. AMD NAVI GPU card,
+	 * it is mandatory to set the right value in specific register
+	 * (offset:0x474) as per the hardware IP specification.
+	 */
+	regmap_write(dev->map, AMD_UCSI_INTR_REG, AMD_UCSI_INTR_EN);
+
+	ret = i2c_dw_acquire_lock(dev);
+	if (ret) {
+		dev_err(dev->dev, "Failed to get bus ownership\n");
+		return ret;
+	}
+
+	dev->msgs = msgs;
+	dev->msgs_num = num_msgs;
+	i2c_dw_xfer_init(dev);
+	i2c_dw_disable_int(dev);
+
+	/* Initiate messages read/write transaction */
+	for (msg_wrt_idx = 0; msg_wrt_idx < num_msgs; msg_wrt_idx++) {
+		tx_buf = msgs[msg_wrt_idx].buf;
+		buf_len = msgs[msg_wrt_idx].len;
+
+		if (!(msgs[msg_wrt_idx].flags & I2C_M_RD))
+			regmap_write(dev->map, DW_IC_TX_TL, buf_len - 1);
+		/*
+		 * Initiate the i2c read/write transaction of buffer length,
+		 * and poll for bus busy status. For the last message transfer,
+		 * update the command with stopbit enable.
+		 */
+		for (msg_itr_lmt = buf_len; msg_itr_lmt > 0; msg_itr_lmt--) {
+			if (msg_wrt_idx == num_msgs - 1 && msg_itr_lmt == 1)
+				cmd |= BIT(9);
+
+			if (msgs[msg_wrt_idx].flags & I2C_M_RD) {
+				/* Due to hardware bug, need to write the same command twice. */
+				regmap_write(dev->map, DW_IC_DATA_CMD, 0x100);
+				regmap_write(dev->map, DW_IC_DATA_CMD, 0x100 | cmd);
+				if (cmd) {
+					regmap_write(dev->map, DW_IC_TX_TL, 2 * (buf_len - 1));
+					regmap_write(dev->map, DW_IC_RX_TL, 2 * (buf_len - 1));
+					/*
+					 * Need to check the stop bit. However, it cannot be
+					 * detected from the registers so we check it always
+					 * when read/write the last byte.
+					 */
+					status = i2c_dw_status(dev);
+					if (status) {
+						ret = -ETIMEDOUT;
+						goto lock_release;
+					}
+					for (data_idx = 0; data_idx < buf_len; data_idx++) {
+						regmap_read(dev->map, DW_IC_DATA_CMD, &val);
+						tx_buf[data_idx] = val;
+					}
+					status = i2c_dw_check_stopbit(dev);
+					if (status) {
+						ret = -ETIMEDOUT;
+						goto lock_release;
+					}
+				}
+			} else {
+				regmap_write(dev->map, DW_IC_DATA_CMD, *tx_buf++ | cmd);
+				usleep_range(AMD_TIMEOUT_MIN_MSEC, AMD_TIMEOUT_MAX_MSEC);
+			}
+		}
+		status = i2c_dw_check_stopbit(dev);
+		if (status) {
+			ret = -ETIMEDOUT;
+			goto lock_release;
+		}
+	}
+
+lock_release:
+	i2c_dw_release_lock(dev);
+
+	return ret;
+}
+
 /*
  * Initiate (and continue) low level master read/write transaction.
  * This function is only called from i2c_dw_isr, and pumping i2c_msg
@@ -461,6 +586,15 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 	dev_dbg(dev->dev, "%s: msgs: %d\n", __func__, num);
 
 	pm_runtime_get_sync(dev->dev);
+	/*
+	 * Initiate I2C message transfer when AMD NAVI GPU card is enabled,
+	 * As it is polling based transfer mechanism, which does not support
+	 * interrupt based functionalities of existing DesignWare driver.
+	 */
+	if (dev->flags & MODEL_AMD_NAVI_GPU) {
+		ret = amd_i2c_dw_xfer_quirk(adap, msgs, num);
+		goto done_nolock;
+	}
 
 	if (dev_WARN_ONCE(dev->dev, dev->suspended, "Transfer while suspended\n")) {
 		ret = -ESHUTDOWN;
@@ -738,6 +872,20 @@ static int i2c_dw_init_recovery_info(struct dw_i2c_dev *dev)
 	return 0;
 }
 
+static int amd_i2c_adap_quirk(struct dw_i2c_dev *dev)
+{
+	struct i2c_adapter *adap = &dev->adapter;
+	int ret;
+
+	pm_runtime_get_noresume(dev->dev);
+	ret = i2c_add_numbered_adapter(adap);
+	if (ret)
+		dev_err(dev->dev, "Failed to add adapter : %d\n", ret);
+	pm_runtime_put_noidle(dev->dev);
+
+	return ret;
+}
+
 int i2c_dw_probe_master(struct dw_i2c_dev *dev)
 {
 	struct i2c_adapter *adap = &dev->adapter;
@@ -774,6 +922,9 @@ int i2c_dw_probe_master(struct dw_i2c_dev *dev)
 	adap->dev.parent = dev->dev;
 	i2c_set_adapdata(adap, dev);
 
+	if (dev->flags & MODEL_AMD_NAVI_GPU)
+		return amd_i2c_adap_quirk(dev);
+
 	if (dev->flags & ACCESS_NO_IRQ_SUSPEND) {
 		irq_flags = IRQF_NO_SUSPEND;
 	} else {
diff --git a/drivers/i2c/busses/i2c-designware-pcidrv.c b/drivers/i2c/busses/i2c-designware-pcidrv.c
index 55c83a7a24f3..e237e9ac1eef 100644
--- a/drivers/i2c/busses/i2c-designware-pcidrv.c
+++ b/drivers/i2c/busses/i2c-designware-pcidrv.c
@@ -26,6 +26,7 @@
 #include "i2c-designware-core.h"
 
 #define DRIVER_NAME "i2c-designware-pci"
+#define AMD_CLK_RATE_HZ	100000
 
 enum dw_pci_ctl_id_t {
 	medfield,
@@ -34,6 +35,7 @@ enum dw_pci_ctl_id_t {
 	cherrytrail,
 	haswell,
 	elkhartlake,
+	navi_amd,
 };
 
 struct dw_scl_sda_cfg {
@@ -78,11 +80,23 @@ static struct dw_scl_sda_cfg hsw_config = {
 	.sda_hold = 0x9,
 };
 
+/* NAVI-AMD HCNT/LCNT/SDA hold time */
+static struct dw_scl_sda_cfg navi_amd_config = {
+	.ss_hcnt = 0x1ae,
+	.ss_lcnt = 0x23a,
+	.sda_hold = 0x9,
+};
+
 static u32 mfld_get_clk_rate_khz(struct dw_i2c_dev *dev)
 {
 	return 25000;
 }
 
+static u32 navi_amd_get_clk_rate_khz(struct dw_i2c_dev *dev)
+{
+	return AMD_CLK_RATE_HZ;
+}
+
 static int mfld_setup(struct pci_dev *pdev, struct dw_pci_controller *c)
 {
 	struct dw_i2c_dev *dev = dev_get_drvdata(&pdev->dev);
@@ -104,6 +118,31 @@ static int mfld_setup(struct pci_dev *pdev, struct dw_pci_controller *c)
 	return -ENODEV;
 }
 
+static int navi_amd_register_client(struct dw_i2c_dev *dev)
+{
+	struct i2c_board_info	info;
+
+	memset(&info, 0, sizeof(struct i2c_board_info));
+	strscpy(info.type, "ccgx-ucsi", I2C_NAME_SIZE);
+	info.addr = 0x08;
+	info.irq = dev->irq;
+
+	dev->slave = i2c_new_client_device(&dev->adapter, &info);
+	if (!dev->slave)
+		return -ENODEV;
+
+	return 0;
+}
+
+static int navi_amd_setup(struct pci_dev *pdev, struct dw_pci_controller *c)
+{
+	struct dw_i2c_dev *dev = dev_get_drvdata(&pdev->dev);
+
+	dev->flags |= MODEL_AMD_NAVI_GPU;
+	dev->timings.bus_freq_hz = I2C_MAX_STANDARD_MODE_FREQ;
+	return 0;
+}
+
 static int mrfld_setup(struct pci_dev *pdev, struct dw_pci_controller *c)
 {
 	/*
@@ -155,6 +194,12 @@ static struct dw_pci_controller dw_pci_controllers[] = {
 		.bus_num = -1,
 		.get_clk_rate_khz = ehl_get_clk_rate_khz,
 	},
+	[navi_amd] = {
+		.bus_num = -1,
+		.scl_sda_cfg = &navi_amd_config,
+		.setup =  navi_amd_setup,
+		.get_clk_rate_khz = navi_amd_get_clk_rate_khz,
+	},
 };
 
 #ifdef CONFIG_PM
@@ -274,6 +319,14 @@ static int i2c_dw_pci_probe(struct pci_dev *pdev,
 		return r;
 	}
 
+	if (dev->flags & MODEL_AMD_NAVI_GPU)
+		r = navi_amd_register_client(dev);
+
+	if (r) {
+		dev_err(dev->dev, "register client failed with %d\n", r);
+		return r;
+	}
+
 	pm_runtime_set_autosuspend_delay(&pdev->dev, 1000);
 	pm_runtime_use_autosuspend(&pdev->dev);
 	pm_runtime_put_autosuspend(&pdev->dev);
@@ -337,6 +390,10 @@ static const struct pci_device_id i2_designware_pci_ids[] = {
 	{ PCI_VDEVICE(INTEL, 0x4bbe), elkhartlake },
 	{ PCI_VDEVICE(INTEL, 0x4bbf), elkhartlake },
 	{ PCI_VDEVICE(INTEL, 0x4bc0), elkhartlake },
+	{ PCI_VDEVICE(ATI,  0x7314), navi_amd },
+	{ PCI_VDEVICE(ATI,  0x73a4), navi_amd },
+	{ PCI_VDEVICE(ATI,  0x73e4), navi_amd },
+	{ PCI_VDEVICE(ATI,  0x73c4), navi_amd },
 	{ 0,}
 };
 MODULE_DEVICE_TABLE(pci, i2_designware_pci_ids);
-- 
2.25.1

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