Hi Peter,
> > 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>
> > Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
> > Reviewed-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> > ---
> > 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
> >
> > 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 | 400
> ++++++++++++++++++++++++++++++++
> > 5 files changed, 435 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 0000000..31884d2
> > --- /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 9ad052a..2d1c5a1 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -6797,6 +6797,13 @@ 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 451d4ae..eed827b 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 18b26af..d499813 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 0000000..4816a31
> > --- /dev/null
> > +++ b/drivers/i2c/busses/i2c-nvidia-gpu.c
> > @@ -0,0 +1,400 @@
> > +// 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_NONE (0 << 2)
> > +#define I2C_MST_CNTL_CMD_READ (1 << 2)
> > +#define I2C_MST_CNTL_CMD_WRITE (2 << 2)
> > +#define I2C_MST_CNTL_GEN_RAB BIT(4)
> > +#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_ADDR_DAB 0
> > +
> > +#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_client *client;
> > + struct mutex mutex; /* to sync read/write */
> > + bool do_start;
>
> I don't think do_start belongs here. master_xfer should always start with a
> start, either explicit if the first message is a write or implicit if it's a read. The
> is no value in keeping this state between different calls to master_xfer. It's
> actually error-prone, see below.
I think do_start is not needed and so will drop it.
> > +};
> > +
> > +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(1000, 2000);
> > + } while (time_is_after_jiffies(target));
> > + if (time_is_before_jiffies(target)) {
> > + dev_err(i2cd->dev, "i2c timeout error %x\n", val);
> > + return -EIO;
> > + }
> > +
> > + 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;
> > + case I2C_MST_CNTL_STATUS_BUS_BUSY:
> > + return -EBUSY;
> > + 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_GEN_STOP |
> > + I2C_MST_CNTL_CMD_READ | (len <<
> I2C_MST_CNTL_BURST_SIZE_SHIFT) |
> > + I2C_MST_CNTL_CYCLE_TRIGGER |
> I2C_MST_CNTL_GEN_NACK;
> > + val &= ~I2C_MST_CNTL_GEN_RAB;
> > + 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, u16 addr) {
> > + u32 val;
> > +
> > + val = addr << I2C_MST_ADDR_DAB;
> > + writel(val, i2cd->regs + I2C_MST_ADDR);
> > +
> > + val = I2C_MST_CNTL_GEN_START | I2C_MST_CNTL_CMD_NONE |
> > + I2C_MST_CNTL_GEN_NACK;
> > + val &= ~(I2C_MST_CNTL_GEN_STOP | I2C_MST_CNTL_GEN_RAB);
> > + writel(val, i2cd->regs + I2C_MST_CNTL);
> > +
> > + return gpu_i2c_check_status(i2cd);
> > +}
> > +
> > +static int gpu_i2c_stop(struct gpu_i2c_dev *i2cd) {
> > + u32 val;
> > +
> > + val = I2C_MST_CNTL_GEN_STOP | I2C_MST_CNTL_CMD_NONE |
> > + I2C_MST_CNTL_GEN_NACK;
> > + val &= ~(I2C_MST_CNTL_GEN_START | I2C_MST_CNTL_GEN_RAB);
> > + writel(val, 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) |
> > + I2C_MST_CNTL_GEN_NACK;
> > + val &= ~(I2C_MST_CNTL_GEN_START | I2C_MST_CNTL_GEN_STOP |
> > + I2C_MST_CNTL_GEN_RAB);
> > + 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;
> > + int i, j;
> > +
> > + mutex_lock(&i2cd->mutex);
> > + for (i = 0; i < num; i++) {
> > + if (msgs[i].flags & I2C_M_RD) {
> > + /* gpu_i2c_read has implicit stop */
>
> Did reads not also have an implicit start? You could mention that explicitly as
> well.
ok
>
> > + status = gpu_i2c_read(i2cd, msgs[i].buf, msgs[i].len);
> > + if (status < 0)
> > + goto unlock;
> > + i2cd->do_start = true;
> > + } else {
>
> And here the problem with the preserved do_start state shows. If the first
> message is a write and do_start happens to be false here, which can happen if
> a previous write failed in the middle, there will be no start before the write
> (and the address is not going to be transferred either).
Ok, will drop do_start.
>
> > + if (i2cd->do_start) {
> > + status = gpu_i2c_start(i2cd, msgs[i].addr);
>
> Why do you need to feed the address to a function that seems to only
> generate a start condition?
Current client address needs to be programmed in I2C_MST_ADDR register.
This has to be programmed once for each client before starting any transfer.
> I mean, the next thing that happens is that the
> address is written explicitly, so why does the hardware need the address
> before that write happens? This bit seems a bit crazy...
This time the address goes as DATA on i2c bus.
> > + if (status < 0)
> > + goto unlock;
> > + status = gpu_i2c_write(i2cd, msgs[i].addr <<
> 1);
>
> You could use i2c_8bit_addr_from_msg(&msgs[i]) here instead of the "magic"
> shift, if you like.
Ok, will use it.
>
> > + if (status < 0)
> > + goto stop;
> > + i2cd->do_start = false;
> > + }
> > + for (j = 0; j < msgs[i].len; j++) {
> > + status = gpu_i2c_write(i2cd, msgs[i].buf[j]);
> > + if (status < 0)
> > + goto stop;
> > + }
> > + /* stop if last write message */
> > + if (i == (num - 1)) {
> > + status = gpu_i2c_stop(i2cd);
> > + if (status < 0)
> > + goto unlock;
> > + i2cd->do_start = true;
> > + }
> > + }
> > + }
> > + status = i;
> > + goto unlock;
> > +stop:
> > + status = gpu_i2c_stop(i2cd);
> > +unlock:
> > + mutex_unlock(&i2cd->mutex);
> > + return status;
> > +}
> > +
> > +static const struct i2c_adapter_quirks gpu_i2c_quirks = {
> > + .flags = I2C_AQ_COMB | I2C_AQ_COMB_WRITE_FIRST |
> I2C_AQ_COMB_SAME_ADDR,
> > + .max_read_len = 4,
> > +};
> > +
> > +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) {
> > + static struct i2c_board_info gpu_ccgx_ucsi = {
> > + I2C_BOARD_INFO("ccgx-ucsi", 0x8),
> > + };
> > +
> > + gpu_ccgx_ucsi.irq = irq;
> > + i2cd->client = i2c_new_device(&i2cd->adapter, &gpu_ccgx_ucsi);
> > + if (!i2cd->client) {
> > + dev_err(i2cd->dev, "i2c_new_device failed\n");
> > + 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(struct gpu_i2c_dev),
> 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;
> > + }
> > +
> > + i2cd->do_start = true;
> > + mutex_init(&i2cd->mutex);
> > + 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) {
> > + dev_err(&pdev->dev, "i2c_add_adapter failed %d\n", status);
>
> I think i2c_add_adapter already barfs in the log on failure. And with more
> details too.
Ok, will drop.
Thanks
Ajay
--
nvpublic
--
>
> Cheers,
> Peter
>
> > + 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;
> > +}
> > +
> > +static int gpu_i2c_idle(struct device *dev) {
> > + struct gpu_i2c_dev *i2cd = dev_get_drvdata(dev);
> > +
> > + if (!mutex_trylock(&i2cd->mutex)) {
> > + dev_info(dev, "-EBUSY\n");
> > + return -EBUSY;
> > + }
> > + mutex_unlock(&i2cd->mutex);
> > +
> > + return 0;
> > +}
> > +
> > +UNIVERSAL_DEV_PM_OPS(gpu_i2c_driver_pm, NULL, gpu_i2c_resume,
> > +gpu_i2c_idle);
> > +
> > +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");
> >
