i2c: add i2c bus driver for amd navi gpu

Latest AMDGPU NAVI cards have USB Type-C interface which can be accessed
over I2C. The Type-C controller has integrated designware i2c which is
exposed as a PCI device to the AMD platform.

Also there exists couple of notable IP problems that are dealt as a
workaround:
- I2C transactions work on a polling mode as IP does not generate
interrupt.

- I2C reads commands are sent twice to address the IP issues.

Reviewed-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Co-developed-by: Nehal Bakulchandra Shah <Nehal-Bakulchandra.shah@amd.com>
Signed-off-by: Nehal Bakulchandra Shah <Nehal-Bakulchandra.shah@amd.com>
Signed-off-by: Sanket Goswami <Sanket.Goswami@amd.com>

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 & AMD_NON_INTR_MODE)
+		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;

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 AMD_NON_INTR_MODE	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);

drivers/i2c/busses/i2c-designware-master.c

@@ -22,6 +22,10 @@
 #include <linux/reset.h>
 
 #include "i2c-designware-core.h"
+#define AMD_TIMEOUT_MSEC_MIN	10000
+#define AMD_TIMEOUT_MSEC_MAX	11000
+#define AMD_FIFO_SIZE		0x20
+#define AMD_MASTERCFG_MASK	GENMASK(15, 0)
 
 static void i2c_dw_configure_fifo_master(struct dw_i2c_dev *dev)
 {
@@ -33,6 +37,154 @@ static void i2c_dw_configure_fifo_master(struct dw_i2c_dev *dev)
 	regmap_write(dev->map, DW_IC_CON, dev->master_cfg);
 }
 
+static void i2c_dw_configure_bus(struct dw_i2c_dev *i2cd)
+{
+	int master_cfg;
+	u16 icon;
+	u32 reg;
+
+	/* First disable the controller */
+	__i2c_dw_disable_nowait(i2cd);
+	master_cfg = DW_IC_CON_MASTER | DW_IC_CON_SLAVE_DISABLE | DW_IC_CON_SPEED_STD;
+
+	/* Clear all the interrupts */
+	regmap_read(i2cd->map, DW_IC_CLR_INTR, &reg);
+	regmap_write(i2cd->map, DW_IC_INTR_MASK, STATUS_IDLE);
+
+	icon = master_cfg & AMD_MASTERCFG_MASK;
+	icon &= ~DW_IC_CON_10BITADDR_MASTER;
+	icon = icon | DW_IC_CON_SPEED_STD;
+
+	/* Configure the master */
+	regmap_write(i2cd->map, DW_IC_CON, icon);
+	/* Configure the FIFO */
+	regmap_write(i2cd->map, DW_IC_TX_TL, AMD_FIFO_SIZE);
+	regmap_write(i2cd->map, DW_IC_RX_TL, AMD_FIFO_SIZE);
+
+	/* Setup 100k Speed */
+	regmap_write(i2cd->map, DW_IC_SS_SCL_HCNT, i2cd->ss_hcnt);
+	regmap_write(i2cd->map, DW_IC_SS_SCL_LCNT, i2cd->ss_lcnt);
+	regmap_write(i2cd->map, DW_IC_TAR, 0x08);
+
+	/* Now enable the controller */
+	__i2c_dw_enable(i2cd);
+}
+
+static int i2c_dw_check_stopbit(struct dw_i2c_dev *i2cd)
+{
+	u32 val;
+	int ret;
+
+	ret = regmap_read_poll_timeout(i2cd->map, DW_IC_INTR_STAT, val,
+				       !(val & DW_IC_INTR_STOP_DET),
+					1100, 20000);
+	if (ret) {
+		dev_err(i2cd->dev, "i2c timeout error %d\n", ret);
+		return -ETIMEDOUT;
+	}
+
+	regmap_read(i2cd->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 *i2cd)
+{
+	int status;
+
+	status = i2c_dw_wait_bus_not_busy(i2cd);
+	if (status)
+		return -ETIMEDOUT;
+
+	status = i2c_dw_check_stopbit(i2cd);
+	if (status)
+		return -ETIMEDOUT;
+
+	return status;
+}
+
+/* Initiate and continue master read/write transaction with polling
+ * based transfer routine and write messages into the tx buffer.
+ */
+static int amd_i2c_dw_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num_msgs)
+{
+	struct dw_i2c_dev *i2cd = 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;
+
+	ret = i2c_dw_acquire_lock(i2cd);
+	if (ret) {
+		dev_err(i2cd->dev, "Failed to get bus ownership\n");
+		return ret;
+	}
+
+	i2c_dw_configure_bus(i2cd);
+
+	/* 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(i2cd->map, DW_IC_TX_TL, buf_len - 1);
+
+		/* Initiate the i2c read/write transition 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 command two times. */
+				regmap_write(i2cd->map, DW_IC_DATA_CMD, 0x100);
+				regmap_write(i2cd->map, DW_IC_DATA_CMD, 0x100 | cmd);
+				if (cmd) {
+					regmap_write(i2cd->map, DW_IC_TX_TL, 2 * (buf_len - 1));
+					regmap_write(i2cd->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(i2cd);
+					if (status) {
+						ret = -ETIMEDOUT;
+						goto lock_release;
+					}
+					for (data_idx = 0; data_idx < buf_len; data_idx++) {
+						regmap_read(i2cd->map, DW_IC_DATA_CMD, &val);
+						tx_buf[data_idx] = val;
+					}
+					status = i2c_dw_check_stopbit(i2cd);
+					if (status) {
+						ret = -ETIMEDOUT;
+						goto lock_release;
+					}
+				}
+			} else {
+				regmap_write(i2cd->map, DW_IC_DATA_CMD, *tx_buf++ | cmd);
+				usleep_range(AMD_TIMEOUT_MSEC_MIN, AMD_TIMEOUT_MSEC_MAX);
+			}
+		}
+		status = i2c_dw_check_stopbit(i2cd);
+		if (status) {
+			ret = -ETIMEDOUT;
+			goto lock_release;
+		}
+	}
+
+lock_release:
+	i2c_dw_release_lock(i2cd);
+
+	return ret;
+}
+
 static int i2c_dw_set_timings_master(struct dw_i2c_dev *dev)
 {
 	const char *mode_str, *fp_str = "";
@@ -208,6 +360,9 @@ static int i2c_dw_init_master(struct dw_i2c_dev *dev)
 	if (dev->sda_hold_time)
 		regmap_write(dev->map, DW_IC_SDA_HOLD, dev->sda_hold_time);
 
+	/* Enable ucsi interrupt */
+	if (dev->flags & AMD_NON_INTR_MODE)
+		regmap_write(dev->map, AMD_UCSI_INTR_REG, AMD_UCSI_INTR_EN);
 	i2c_dw_configure_fifo_master(dev);
 	i2c_dw_release_lock(dev);
 
@@ -462,6 +617,9 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 
 	pm_runtime_get_sync(dev->dev);
 
+	if (dev->flags & AMD_NON_INTR_MODE)
+		return amd_i2c_dw_master_xfer(adap, msgs, num);
+
 	if (dev_WARN_ONCE(dev->dev, dev->suspended, "Transfer while suspended\n")) {
 		ret = -ESHUTDOWN;
 		goto done_nolock;
@@ -738,6 +896,19 @@ static int i2c_dw_init_recovery_info(struct dw_i2c_dev *dev)
 	return 0;
 }
 
+int amd_i2c_adap_quirk(struct dw_i2c_dev *amdev)
+{
+	struct i2c_adapter *amdap = &amdev->adapter;
+	int ret;
+
+	if (!(amdev->flags & AMD_NON_INTR_MODE))
+		return -ENODEV;
+
+	return i2c_add_numbered_adapter(amdap);
+
+	return ret;
+}
+
 int i2c_dw_probe_master(struct dw_i2c_dev *dev)
 {
 	struct i2c_adapter *adap = &dev->adapter;
@@ -774,6 +945,10 @@ int i2c_dw_probe_master(struct dw_i2c_dev *dev)
 	adap->dev.parent = dev->dev;
 	i2c_set_adapdata(adap, dev);
 
+	ret = amd_i2c_adap_quirk(dev);
+	if (ret != -ENODEV)
+		return ret;
+
 	if (dev->flags & ACCESS_NO_IRQ_SUSPEND) {
 		irq_flags = IRQF_NO_SUSPEND;
 	} else {

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	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;
+}
+
 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 +118,35 @@ static int mfld_setup(struct pci_dev *pdev, struct dw_pci_controller *c)
 	return -ENODEV;
 }
 
+static int i2c_dw_populate_client(struct dw_i2c_dev *i2cd)
+{
+	struct i2c_board_info	*i2c_dw_ccgx_ucsi;
+	struct i2c_client	*ccgx_client;
+
+	i2c_dw_ccgx_ucsi = devm_kzalloc(i2cd->dev, sizeof(*i2c_dw_ccgx_ucsi), GFP_KERNEL);
+	if (!i2c_dw_ccgx_ucsi)
+		return -ENOMEM;
+
+	strscpy(i2c_dw_ccgx_ucsi->type, "ccgx-ucsi", sizeof(i2c_dw_ccgx_ucsi->type));
+	i2c_dw_ccgx_ucsi->addr = 0x08;
+	i2c_dw_ccgx_ucsi->irq = i2cd->irq;
+
+	ccgx_client = i2c_new_client_device(&i2cd->adapter, i2c_dw_ccgx_ucsi);
+	if (!ccgx_client)
+		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 |= AMD_NON_INTR_MODE;
+	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 +198,12 @@ 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 +323,9 @@ static int i2c_dw_pci_probe(struct pci_dev *pdev,
 		return r;
 	}
 
+	if (dev->flags & AMD_NON_INTR_MODE)
+		i2c_dw_populate_client(dev);
+
 	pm_runtime_set_autosuspend_delay(&pdev->dev, 1000);
 	pm_runtime_use_autosuspend(&pdev->dev);
 	pm_runtime_put_autosuspend(&pdev->dev);
@@ -337,6 +389,10 @@ 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);