Latest NVIDIA GPU card has USB Type-C interface. There is a
Type-C controller which can be accessed over I2C.
This driver adds I2C bus driver to communicate with Type-C controller.
I2C client driver will be part of USB Type-C UCSI driver.
Signed-off-by: Ajay Gupta <ajayg@xxxxxxxxxx>
---
Changes from v1 -> v2
None
Changes from v2 -> v3
Fixed review comments from Andy and Thierry
Rename i2c-gpu.c -> i2c-nvidia-gpu.c
Changes from v3 -> v4
Fixed review comments from Andy
Changes from v4 -> v5
Fixed review comments from Andy
Changes from v5 -> v6
None
Changes from v6 -> v7 -> v8
Fixed review comments from Peter
- Add implicit STOP for last write message
- Add i2c_adapter_quirks with max_read_len and
I2C_AQ_COMB flags
Changes from v8 -> v9
Fixed review comments from Peter
- Drop do_start flag
- Use i2c_8bit_addr_from_msg()
Changes from v9 -> v10
Fixed review comments from Peter
- Dropped I2C_FUNC_SMBUS_EMUL
- Dropped local mutex
Changes from v10 -> v11
Fixed review comments from Peter
- Moved stop in master_xfer at end of message
- Change i2c_read without STOP
- Dropped I2C_AC_COMB* flags
Changes from v11 -> v12
Fixed review comments from Peter
- Removed clearing of empty bits
- Fix master_xfer for correct stop use
Changes from v12 -> v13
Fixed review comments from Peter
- Added comments on 4 byte read limitation
- Added I2C_AC_COMB* flags
Changes from v13 -> v14 -> v15
None
Documentation/i2c/busses/i2c-nvidia-gpu | 18 ++
MAINTAINERS | 7 +
drivers/i2c/busses/Kconfig | 9 +
drivers/i2c/busses/Makefile | 1 +
drivers/i2c/busses/i2c-nvidia-gpu.c | 368 ++++++++++++++++++++++++
5 files changed, 403 insertions(+)
create mode 100644 Documentation/i2c/busses/i2c-nvidia-gpu
create mode 100644 drivers/i2c/busses/i2c-nvidia-gpu.c
diff --git a/Documentation/i2c/busses/i2c-nvidia-gpu b/Documentation/i2c/busses/i2c-nvidia-gpu
new file mode 100644
index 000000000000..31884d2b2eb5
--- /dev/null
+++ b/Documentation/i2c/busses/i2c-nvidia-gpu
@@ -0,0 +1,18 @@
+Kernel driver i2c-nvidia-gpu
+
+Datasheet: not publicly available.
+
+Authors:
+ Ajay Gupta <ajayg@xxxxxxxxxx>
+
+Description
+-----------
+
+i2c-nvidia-gpu is a driver for I2C controller included in NVIDIA Turing
+and later GPUs and it is used to communicate with Type-C controller on GPUs.
+
+If your 'lspci -v' listing shows something like the following,
+
+01:00.3 Serial bus controller [0c80]: NVIDIA Corporation Device 1ad9 (rev a1)
+
+then this driver should support the I2C controller of your GPU.
diff --git a/MAINTAINERS b/MAINTAINERS
index bd702ad56c7f..5885a0931de9 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6843,6 +6843,13 @@ L: linux-acpi@xxxxxxxxxxxxxxx
S: Maintained
F: drivers/i2c/i2c-core-acpi.c
+I2C CONTROLLER DRIVER FOR NVIDIA GPU
+M: Ajay Gupta <ajayg@xxxxxxxxxx>
+L: linux-i2c@xxxxxxxxxxxxxxx
+S: Maintained
+F: Documentation/i2c/busses/i2c-nvidia-gpu
+F: drivers/i2c/busses/i2c-nvidia-gpu.c
+
I2C MUXES
M: Peter Rosin <peda@xxxxxxxxxx>
L: linux-i2c@xxxxxxxxxxxxxxx
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 451d4ae50e66..eed827b44068 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -224,6 +224,15 @@ config I2C_NFORCE2_S4985
This driver can also be built as a module. If so, the module
will be called i2c-nforce2-s4985.
+config I2C_NVIDIA_GPU
+ tristate "NVIDIA GPU I2C controller"
+ depends on PCI
+ help
+ If you say yes to this option, support will be included for the
+ NVIDIA GPU I2C controller which is used to communicate with the GPU's
+ Type-C controller. This driver can also be built as a module called
+ i2c-nvidia-gpu.
+
config I2C_SIS5595
tristate "SiS 5595"
depends on PCI
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 18b26af82b1c..d499813df038 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -140,5 +140,6 @@ obj-$(CONFIG_I2C_SIBYTE) += i2c-sibyte.o
obj-$(CONFIG_I2C_XGENE_SLIMPRO) += i2c-xgene-slimpro.o
obj-$(CONFIG_SCx200_ACB) += scx200_acb.o
obj-$(CONFIG_I2C_FSI) += i2c-fsi.o
+obj-$(CONFIG_I2C_NVIDIA_GPU) += i2c-nvidia-gpu.o
ccflags-$(CONFIG_I2C_DEBUG_BUS) := -DDEBUG
diff --git a/drivers/i2c/busses/i2c-nvidia-gpu.c b/drivers/i2c/busses/i2c-nvidia-gpu.c
new file mode 100644
index 000000000000..744f5e42636b
--- /dev/null
+++ b/drivers/i2c/busses/i2c-nvidia-gpu.c
@@ -0,0 +1,368 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Nvidia GPU I2C controller Driver
+ *
+ * Copyright (C) 2018 NVIDIA Corporation. All rights reserved.
+ * Author: Ajay Gupta <ajayg@xxxxxxxxxx>
+ */
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/platform_device.h>
+#include <linux/pm.h>
+#include <linux/pm_runtime.h>
+
+#include <asm/unaligned.h>
+
+/* I2C definitions */
+#define I2C_MST_CNTL 0x00
+#define I2C_MST_CNTL_GEN_START BIT(0)
+#define I2C_MST_CNTL_GEN_STOP BIT(1)
+#define I2C_MST_CNTL_CMD_READ (1 << 2)
+#define I2C_MST_CNTL_CMD_WRITE (2 << 2)
+#define I2C_MST_CNTL_BURST_SIZE_SHIFT 6
+#define I2C_MST_CNTL_GEN_NACK BIT(28)
+#define I2C_MST_CNTL_STATUS GENMASK(30, 29)
+#define I2C_MST_CNTL_STATUS_OKAY (0 << 29)
+#define I2C_MST_CNTL_STATUS_NO_ACK (1 << 29)
+#define I2C_MST_CNTL_STATUS_TIMEOUT (2 << 29)
+#define I2C_MST_CNTL_STATUS_BUS_BUSY (3 << 29)
+#define I2C_MST_CNTL_CYCLE_TRIGGER BIT(31)
+
+#define I2C_MST_ADDR 0x04
+
+#define I2C_MST_I2C0_TIMING 0x08
+#define I2C_MST_I2C0_TIMING_SCL_PERIOD_100KHZ 0x10e
+#define I2C_MST_I2C0_TIMING_TIMEOUT_CLK_CNT 16
+#define I2C_MST_I2C0_TIMING_TIMEOUT_CLK_CNT_MAX 255
+#define I2C_MST_I2C0_TIMING_TIMEOUT_CHECK BIT(24)
+
+#define I2C_MST_DATA 0x0c
+
+#define I2C_MST_HYBRID_PADCTL 0x20
+#define I2C_MST_HYBRID_PADCTL_MODE_I2C BIT(0)
+#define I2C_MST_HYBRID_PADCTL_I2C_SCL_INPUT_RCV BIT(14)
+#define I2C_MST_HYBRID_PADCTL_I2C_SDA_INPUT_RCV BIT(15)
+
+struct gpu_i2c_dev {
+ struct device *dev;
+ void __iomem *regs;
+ struct i2c_adapter adapter;
+ struct i2c_board_info *gpu_ccgx_ucsi;
+};
+
+static void gpu_enable_i2c_bus(struct gpu_i2c_dev *i2cd)
+{
+ u32 val;
+
+ /* enable I2C */
+ val = readl(i2cd->regs + I2C_MST_HYBRID_PADCTL);
+ val |= I2C_MST_HYBRID_PADCTL_MODE_I2C |
+ I2C_MST_HYBRID_PADCTL_I2C_SCL_INPUT_RCV |
+ I2C_MST_HYBRID_PADCTL_I2C_SDA_INPUT_RCV;
+ writel(val, i2cd->regs + I2C_MST_HYBRID_PADCTL);
+
+ /* enable 100KHZ mode */
+ val = I2C_MST_I2C0_TIMING_SCL_PERIOD_100KHZ;
+ val |= (I2C_MST_I2C0_TIMING_TIMEOUT_CLK_CNT_MAX
+ << I2C_MST_I2C0_TIMING_TIMEOUT_CLK_CNT);
+ val |= I2C_MST_I2C0_TIMING_TIMEOUT_CHECK;
+ writel(val, i2cd->regs + I2C_MST_I2C0_TIMING);
+}
+
+static int gpu_i2c_check_status(struct gpu_i2c_dev *i2cd)
+{
+ unsigned long target = jiffies + msecs_to_jiffies(1000);
+ u32 val;
+
+ do {
+ val = readl(i2cd->regs + I2C_MST_CNTL);
+ if (!(val & I2C_MST_CNTL_CYCLE_TRIGGER))
+ break;
+ if ((val & I2C_MST_CNTL_STATUS) !=
+ I2C_MST_CNTL_STATUS_BUS_BUSY)
+ break;
+ usleep_range(500, 600);
+ } while (time_is_after_jiffies(target));
+
+ if (time_is_before_jiffies(target)) {
+ dev_err(i2cd->dev, "i2c timeout error %x\n", val);
+ return -ETIME;
+ }
+
+ val = readl(i2cd->regs + I2C_MST_CNTL);
+ switch (val & I2C_MST_CNTL_STATUS) {
+ case I2C_MST_CNTL_STATUS_OKAY:
+ return 0;
+ case I2C_MST_CNTL_STATUS_NO_ACK:
+ return -EIO;
+ case I2C_MST_CNTL_STATUS_TIMEOUT:
+ return -ETIME;
+ default:
+ return 0;
+ }
+}
+
+static int gpu_i2c_read(struct gpu_i2c_dev *i2cd, u8 *data, u16 len)
+{
+ int status;
+ u32 val;
+
+ val = I2C_MST_CNTL_GEN_START | I2C_MST_CNTL_CMD_READ |
+ (len << I2C_MST_CNTL_BURST_SIZE_SHIFT) |
+ I2C_MST_CNTL_CYCLE_TRIGGER | I2C_MST_CNTL_GEN_NACK;
+ writel(val, i2cd->regs + I2C_MST_CNTL);
+
+ status = gpu_i2c_check_status(i2cd);
+ if (status < 0)
+ return status;
+
+ val = readl(i2cd->regs + I2C_MST_DATA);
+ switch (len) {
+ case 1:
+ data[0] = val;
+ break;
+ case 2:
+ put_unaligned_be16(val, data);
+ break;
+ case 3:
+ put_unaligned_be16(val >> 8, data);
+ data[2] = val;
+ break;
+ case 4:
+ put_unaligned_be32(val, data);
+ break;
+ default:
+ break;
+ }
+ return status;
+}
+
+static int gpu_i2c_start(struct gpu_i2c_dev *i2cd)
+{
+ writel(I2C_MST_CNTL_GEN_START, i2cd->regs + I2C_MST_CNTL);
+ return gpu_i2c_check_status(i2cd);
+}
+
+static int gpu_i2c_stop(struct gpu_i2c_dev *i2cd)
+{
+ writel(I2C_MST_CNTL_GEN_STOP, i2cd->regs + I2C_MST_CNTL);
+ return gpu_i2c_check_status(i2cd);
+}
+
+static int gpu_i2c_write(struct gpu_i2c_dev *i2cd, u8 data)
+{
+ u32 val;
+
+ writel(data, i2cd->regs + I2C_MST_DATA);
+
+ val = I2C_MST_CNTL_CMD_WRITE | (1 << I2C_MST_CNTL_BURST_SIZE_SHIFT);
+ writel(val, i2cd->regs + I2C_MST_CNTL);
+
+ return gpu_i2c_check_status(i2cd);
+}
+
+static int gpu_i2c_master_xfer(struct i2c_adapter *adap,
+ struct i2c_msg *msgs, int num)
+{
+ struct gpu_i2c_dev *i2cd = i2c_get_adapdata(adap);
+ int status, status2;
+ int i, j;
+
+ /*
+ * The controller supports maximum 4 byte read due to known
+ * limitation of sending STOP after every read.
+ */
+ for (i = 0; i < num; i++) {
+ if (msgs[i].flags & I2C_M_RD) {
+ /* program client address before starting read */
+ writel(msgs[i].addr, i2cd->regs + I2C_MST_ADDR);
+ /* gpu_i2c_read has implicit start */
+ status = gpu_i2c_read(i2cd, msgs[i].buf, msgs[i].len);
+ if (status < 0)
+ goto stop;
+ } else {
+ u8 addr = i2c_8bit_addr_from_msg(msgs + i);
+
+ status = gpu_i2c_start(i2cd);
+ if (status < 0) {
+ if (i == 0)
+ return status;
+ goto stop;
+ }
+
+ status = gpu_i2c_write(i2cd, addr);
+ if (status < 0)
+ goto stop;
+
+ for (j = 0; j < msgs[i].len; j++) {
+ status = gpu_i2c_write(i2cd, msgs[i].buf[j]);
+ if (status < 0)
+ goto stop;
+ }
+ }
+ }
+ status = gpu_i2c_stop(i2cd);
+ if (status < 0)
+ return status;
+
+ return i;
+stop:
+ status2 = gpu_i2c_stop(i2cd);
+ if (status2 < 0)
+ dev_err(i2cd->dev, "i2c stop failed %d\n", status2);
+ return status;
+}
+
+static const struct i2c_adapter_quirks gpu_i2c_quirks = {
+ .max_read_len = 4,
+ .flags = I2C_AQ_COMB_WRITE_THEN_READ,
+};
+
+static u32 gpu_i2c_functionality(struct i2c_adapter *adap)
+{
+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm gpu_i2c_algorithm = {
+ .master_xfer = gpu_i2c_master_xfer,
+ .functionality = gpu_i2c_functionality,
+};
+
+/*
+ * This driver is for Nvidia GPU cards with USB Type-C interface.
+ * We want to identify the cards using vendor ID and class code only
+ * to avoid dependency of adding product id for any new card which
+ * requires this driver.
+ * Currently there is no class code defined for UCSI device over PCI
+ * so using UNKNOWN class for now and it will be updated when UCSI
+ * over PCI gets a class code.
+ * There is no other NVIDIA cards with UNKNOWN class code. Even if the
+ * driver gets loaded for an undesired card then eventually i2c_read()
+ * (initiated from UCSI i2c_client) will timeout or UCSI commands will
+ * timeout.
+ */
+#define PCI_CLASS_SERIAL_UNKNOWN 0x0c80
+static const struct pci_device_id gpu_i2c_ids[] = {
+ { PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
+ PCI_CLASS_SERIAL_UNKNOWN << 8, 0xffffff00},
+ { }
+};
+MODULE_DEVICE_TABLE(pci, gpu_i2c_ids);
+
+static int gpu_populate_client(struct gpu_i2c_dev *i2cd, int irq)
+{
+ struct i2c_client *ccgx_client;
+
+ i2cd->gpu_ccgx_ucsi = devm_kzalloc(i2cd->dev,
+ sizeof(*i2cd->gpu_ccgx_ucsi),
+ GFP_KERNEL);
+ if (!i2cd->gpu_ccgx_ucsi)
+ return -ENOMEM;
+
+ strlcpy(i2cd->gpu_ccgx_ucsi->type, "ccgx-ucsi",
+ sizeof(i2cd->gpu_ccgx_ucsi->type));
+ i2cd->gpu_ccgx_ucsi->addr = 0x8;
+ i2cd->gpu_ccgx_ucsi->irq = irq;
+ ccgx_client = i2c_new_device(&i2cd->adapter, i2cd->gpu_ccgx_ucsi);
+ if (!ccgx_client)
+ return -ENODEV;
+
+ return 0;
+}
+
+static int gpu_i2c_probe(struct pci_dev *pdev, const struct pci_device_id *id)
+{
+ struct gpu_i2c_dev *i2cd;
+ int status;
+
+ i2cd = devm_kzalloc(&pdev->dev, sizeof(*i2cd), GFP_KERNEL);
+ if (!i2cd)
+ return -ENOMEM;
+
+ i2cd->dev = &pdev->dev;
+ dev_set_drvdata(&pdev->dev, i2cd);
+
+ status = pcim_enable_device(pdev);
+ if (status < 0) {
+ dev_err(&pdev->dev, "pcim_enable_device failed %d\n", status);
+ return status;
+ }
+
+ pci_set_master(pdev);
+
+ i2cd->regs = pcim_iomap(pdev, 0, 0);
+ if (!i2cd->regs) {
+ dev_err(&pdev->dev, "pcim_iomap failed\n");
+ return -ENOMEM;
+ }
+
+ status = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSI);
+ if (status < 0) {
+ dev_err(&pdev->dev, "pci_alloc_irq_vectors err %d\n", status);
+ return status;
+ }
+
+ gpu_enable_i2c_bus(i2cd);
+
+ i2c_set_adapdata(&i2cd->adapter, i2cd);
+ i2cd->adapter.owner = THIS_MODULE;
+ strlcpy(i2cd->adapter.name, "NVIDIA GPU I2C adapter",
+ sizeof(i2cd->adapter.name));
+ i2cd->adapter.algo = &gpu_i2c_algorithm;
+ i2cd->adapter.quirks = &gpu_i2c_quirks;
+ i2cd->adapter.dev.parent = &pdev->dev;
+ status = i2c_add_adapter(&i2cd->adapter);
+ if (status < 0)
+ goto free_irq_vectors;
+
+ status = gpu_populate_client(i2cd, pdev->irq);
+ if (status < 0) {
+ dev_err(&pdev->dev, "gpu_populate_client failed %d\n", status);
+ goto del_adapter;
+ }
+
+ return 0;
+
+del_adapter:
+ i2c_del_adapter(&i2cd->adapter);
+free_irq_vectors:
+ pci_free_irq_vectors(pdev);
+ return status;
+}
+
+static void gpu_i2c_remove(struct pci_dev *pdev)
+{
+ struct gpu_i2c_dev *i2cd = dev_get_drvdata(&pdev->dev);
+
+ i2c_del_adapter(&i2cd->adapter);
+ pci_free_irq_vectors(pdev);
+}
+
+static int gpu_i2c_resume(struct device *dev)
+{
+ struct gpu_i2c_dev *i2cd = dev_get_drvdata(dev);
+
+ gpu_enable_i2c_bus(i2cd);
+ return 0;
+}
+
+UNIVERSAL_DEV_PM_OPS(gpu_i2c_driver_pm, NULL, gpu_i2c_resume, NULL);
+
+static struct pci_driver gpu_i2c_driver = {
+ .name = "nvidia-gpu",
+ .id_table = gpu_i2c_ids,
+ .probe = gpu_i2c_probe,
+ .remove = gpu_i2c_remove,
+ .driver = {
+ .pm = &gpu_i2c_driver_pm,
+ },
+};
+
+module_pci_driver(gpu_i2c_driver);
+
+MODULE_AUTHOR("Ajay Gupta <ajayg@xxxxxxxxxx>");
+MODULE_DESCRIPTION("Nvidia GPU I2C controller Driver");
+MODULE_LICENSE("GPL v2");
--
2.17.1
