Hi Peter, > > 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 > > Changes from v8 -> v9 > > Fixed review comments from Peter > > - Drop do_start flag > > - Use i2c_8bit_addr_from_msg() > > > > 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 | 396 > ++++++++++++++++++++++++++++++++ > > 5 files changed, 431 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..4a63a4e4 > > --- /dev/null > > +++ b/drivers/i2c/busses/i2c-nvidia-gpu.c > > @@ -0,0 +1,396 @@ > > +// 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 */ > > Hmm, what do you need to sync read/write with? What if there are multiple clients and each of them wants to use I2C bus for read/write? Even in UCSI client, user may want to change alt mode which will result in read/write request in a thread. So we have to synchronize between UCSI ISR and the user thread. > The only thing I can find is > that busy-check in gpu_i2c_idle, but can runtime-pm really try to idle an > adapter that has an xfer in flight? If that's the case, what stops a new xfer from > being initiated after runtime-pm has checked if > ->runtime_idle returns ok but before the device is really suspended? > > PM is not an area I'm familiar with, so it's an honest question. > > > +}; > > + > > +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 start and stop */ > > + status = gpu_i2c_read(i2cd, msgs[i].buf, msgs[i].len); > > Per your comments on v8, the address has to be programmed before the > transfer, but you fail to do that if the first message is a read. This will never happen. Hint: I2C_AQ_COMB_WRITE_FIRST > Is the I2C_MST_ADDR register really in the loop when you do a write? That’s not needed. We need to write I2C_MST_ADDR once before starting one or more transfers to a client. > Because > I think it would simplify things if you could move the write to the > I2C_MST_ADDR register to be in gpu_i2c_read instead of in gpu_i2c_start. Or, > maybe just write to I2C_MST_ADDR before the for-loop in this function. See above. Hint: I2C_AQ_COMB_WRITE_FIRST > > + if (status < 0) > > + goto unlock; > > + } else { > > + /* start on first write message */ > > + if (i == 0) { > > You do not issue a restart nor do you write the address to the bus for the > second message, if it's a write. That’s not needed. We need to write I2C_MST_ADDR once before starting one or more transfers to a client. > That makes me wonder if this patch was > tested, because AFAICT ccg_write in patch 2/2 uses xfers combining two write > messages and I fail to see how that can work? See above. > Also, have you verified if gpu_i2c_start really issues a restart instead of a stop > followed by a start if the bus is not idle on function entry? Yes. Hint: refer gpu_i2_start() and look for I2C_MST_CNTL_GEN_STOP bit. Thanks Ajay -- nvpublic -- > Or is the > documentation clear on this detail? Might be worth checking anyway, as > documentation is not always completely correct... > > Cheers, > Peter > > > + u8 addr = i2c_8bit_addr_from_msg(msgs + i); > > + status = gpu_i2c_start(i2cd, msgs[i].addr); > > + if (status < 0) > > + goto unlock; > > + > > + 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; > > + } > > + /* stop if last write message */ > > + if (i == (num - 1)) { > > + status = gpu_i2c_stop(i2cd); > > + if (status < 0) > > + goto unlock; > > + } > > + } > > + } > > + 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; > > + } > > + > > + 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) > > + 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"); > >