Hi Andy,
> > 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.
> >
>
> Some small comments below, after addressing them
>
> Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
>
> > 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
> >
> > 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 | 389
> ++++++++++++++++++++++++++++++++
> > 5 files changed, 424 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..fa01187
> > --- /dev/null
> > +++ b/drivers/i2c/busses/i2c-nvidia-gpu.c
> > @@ -0,0 +1,389 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Nvidia GPU I2C controller Driver
> > + *
> > + * Copyright (C) 2018 NVIDIA Corporation. All rights reserved.
> > + * Author: Ajay Gupta <ajayg@xxxxxxxxxx>
>
> > + *
>
> Redundant line.
>
> > + */
ok
>
> > +#include <asm/unaligned.h>
>
> This should go after linux/* ones...
>
> > +#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>
> > +
>
> ...here.
will fix
>
> > +/* I2C definitions */
> > +#define I2C_MST_CNTL 0x0
> > +#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)
>
> Redundant parens
>
> > +#define I2C_MST_CNTL_GEN_NACK BIT(28)
> > +#define I2C_MST_CNTL_STATUS (3 << 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 pci_dev *pci_dev;
>
> This should be a good argument why you are keeping struct pci_dev instead of
> struct device.
sure
>
> > + void __iomem *regs;
> > + struct i2c_adapter adapter;
> > + struct i2c_client *client;
> > + struct mutex mutex; /* to sync read/write */
> > + bool do_start;
> > +};
> > +
> > +static void 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 i2c_check_status(struct gpu_i2c_dev *i2cd) {
> > + unsigned long target = jiffies + msecs_to_jiffies(1000);
>
> > + int status = -EIO;
>
> You can get rid of this variable by returning in place.
Sounds good
>
> > + u32 val;
> > +
> > + do {
> > + val = readl(i2cd->regs + I2C_MST_CNTL);
> > + if ((val & I2C_MST_CNTL_CYCLE_TRIGGER) !=
> > + 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))
> > + return status;
> > +
> > + val = readl(i2cd->regs + I2C_MST_CNTL);
> > + switch (val & I2C_MST_CNTL_STATUS) {
> > + case I2C_MST_CNTL_STATUS_OKAY:
> > + status = 0;
> > + break;
> > + case I2C_MST_CNTL_STATUS_NO_ACK:
> > + status = -EIO;
> > + break;
> > + case I2C_MST_CNTL_STATUS_TIMEOUT:
> > + status = -ETIME;
> > + break;
> > + case I2C_MST_CNTL_STATUS_BUS_BUSY:
> > + status = -EBUSY;
> > + break;
> > + default:
> > + break;
> > + }
> > + return status;
> > +}
> > +
> > +static int i2c_read(struct gpu_i2c_dev *i2cd, u8 *data, u16 len) {
> > + int status;
> > + u32 val = 0;
> > +
> > + 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 = 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 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 i2c_check_status(i2cd); }
> > +
> > +static int 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 i2c_check_status(i2cd); }
> > +
> > +static int 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 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);
> > + struct device *dev = &i2cd->pci_dev->dev;
>
> > + int sts;
>
> Btw, be consistent with names, status looks slightly better.
ok
>
> > + int i, j;
> > +
> > + mutex_lock(&i2cd->mutex);
> > + for (i = 0; i < num; i++) {
> > + if (msgs[i].flags & I2C_M_RD) {
> > + sts = i2c_read(i2cd, msgs[i].buf, msgs[i].len);
> > + if (sts < 0) {
> > + dev_err(dev, "i2c_read error %x", sts);
> > + break;
> > + }
> > + i2cd->do_start = true;
> > + } else if (msgs[i].flags & I2C_M_STOP) {
> > + sts = i2c_stop(i2cd);
> > + if (sts < 0) {
> > + dev_err(dev, "i2c_stop error %x", sts);
> > + goto unlock;
> > + }
> > + i2cd->do_start = true;
> > + } else {
> > + if (i2cd->do_start) {
> > + sts = i2c_start(i2cd, msgs[i].addr);
> > + if (sts < 0) {
> > + dev_err(dev, "i2c_start error %x", sts);
> > + goto unlock;
> > + }
> > + sts = i2c_write(i2cd, msgs[i].addr << 1);
> > + if (sts < 0) {
> > + dev_err(dev, "i2c_write error %x", sts);
> > + goto stop;
> > + }
> > + i2cd->do_start = false;
> > + }
> > + for (j = 0; j < msgs[i].len; j++) {
> > + sts = i2c_write(i2cd, *(msgs[i].buf + j));
> > + if (sts < 0) {
> > + dev_err(dev, "i2c_write error %x", sts);
> > + goto stop;
> > + }
> > + }
> > + }
> > + }
> > + goto unlock;
> > +stop:
> > + sts = i2c_stop(i2cd);
> > + if (sts < 0)
> > + dev_err(dev, "i2c_stop error %x", sts);
> > +unlock:
> > + mutex_unlock(&i2cd->mutex);
> > + return i;
> > +}
> > +
> > +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, };
> > +
>
> > +#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},
> > + { }
> > +};
>
> I'm really in doubt how it's supposed to be enumerated without conflicts or
> shadowing other hardware.
> Explain in the comments, please.
Will add comments.
>
> > +MODULE_DEVICE_TABLE(pci, gpu_i2c_ids);
> > +
> > +static int gpu_i2c_probe(struct pci_dev *dev, const struct
> > +pci_device_id *id) {
>
> > + struct i2c_board_info gpu_i2c_ucsi_board_info = {
> > + I2C_BOARD_INFO("ccgx-ucsi", 0x8)
> > + };
>
> Can't you rather put this as static const which is provided in driver_data above
Can't add as "const" since I am saving "irq" field from pci_dev->irq
but will add new function gpu_populate_client()
Thanks
Ajay
--
nvpublic
--
