drivers/i2c/busses/i2c-nvidia-gpu.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Nvidia GPU I2C controller Driver
   4  *
   5  * Copyright (C) 2018 NVIDIA Corporation. All rights reserved.
   6  * Author: Ajay Gupta <ajayg@nvidia.com>
   7  */
   8 #include <linux/delay.h>
   9 #include <linux/i2c.h>
  10 #include <linux/interrupt.h>
  11 #include <linux/module.h>
  12 #include <linux/pci.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/pm.h>
  15 #include <linux/pm_runtime.h>
  16
  17 #include <asm/unaligned.h>
  18
  19 /* I2C definitions */
  20 #define I2C_MST_CNTL                            0x00
  21 #define I2C_MST_CNTL_GEN_START                  BIT(0)
  22 #define I2C_MST_CNTL_GEN_STOP                   BIT(1)
  23 #define I2C_MST_CNTL_CMD_READ                   (1 << 2)
  24 #define I2C_MST_CNTL_CMD_WRITE                  (2 << 2)
  25 #define I2C_MST_CNTL_BURST_SIZE_SHIFT           6
  26 #define I2C_MST_CNTL_GEN_NACK                   BIT(28)
  27 #define I2C_MST_CNTL_STATUS                     GENMASK(30, 29)
  28 #define I2C_MST_CNTL_STATUS_OKAY                (0 << 29)
  29 #define I2C_MST_CNTL_STATUS_NO_ACK              (1 << 29)
  30 #define I2C_MST_CNTL_STATUS_TIMEOUT             (2 << 29)
  31 #define I2C_MST_CNTL_STATUS_BUS_BUSY            (3 << 29)
  32 #define I2C_MST_CNTL_CYCLE_TRIGGER              BIT(31)
  33
  34 #define I2C_MST_ADDR                            0x04
  35
  36 #define I2C_MST_I2C0_TIMING                             0x08
  37 #define I2C_MST_I2C0_TIMING_SCL_PERIOD_100KHZ           0x10e
  38 #define I2C_MST_I2C0_TIMING_TIMEOUT_CLK_CNT             16
  39 #define I2C_MST_I2C0_TIMING_TIMEOUT_CLK_CNT_MAX         255
  40 #define I2C_MST_I2C0_TIMING_TIMEOUT_CHECK               BIT(24)
  41
  42 #define I2C_MST_DATA                                    0x0c
  43
  44 #define I2C_MST_HYBRID_PADCTL                           0x20
  45 #define I2C_MST_HYBRID_PADCTL_MODE_I2C                  BIT(0)
  46 #define I2C_MST_HYBRID_PADCTL_I2C_SCL_INPUT_RCV         BIT(14)
  47 #define I2C_MST_HYBRID_PADCTL_I2C_SDA_INPUT_RCV         BIT(15)
  48
  49 struct gpu_i2c_dev {
  50         struct device *dev;
  51         void __iomem *regs;
  52         struct i2c_adapter adapter;
  53         struct i2c_board_info *gpu_ccgx_ucsi;
  54 };
  55
  56 static void gpu_enable_i2c_bus(struct gpu_i2c_dev *i2cd)
  57 {
  58         u32 val;
  59
  60         /* enable I2C */
  61         val = readl(i2cd->regs + I2C_MST_HYBRID_PADCTL);
  62         val |= I2C_MST_HYBRID_PADCTL_MODE_I2C |
  63                 I2C_MST_HYBRID_PADCTL_I2C_SCL_INPUT_RCV |
  64                 I2C_MST_HYBRID_PADCTL_I2C_SDA_INPUT_RCV;
  65         writel(val, i2cd->regs + I2C_MST_HYBRID_PADCTL);
  66
  67         /* enable 100KHZ mode */
  68         val = I2C_MST_I2C0_TIMING_SCL_PERIOD_100KHZ;
  69         val |= (I2C_MST_I2C0_TIMING_TIMEOUT_CLK_CNT_MAX
  70             << I2C_MST_I2C0_TIMING_TIMEOUT_CLK_CNT);
  71         val |= I2C_MST_I2C0_TIMING_TIMEOUT_CHECK;
  72         writel(val, i2cd->regs + I2C_MST_I2C0_TIMING);
  73 }
  74
  75 static int gpu_i2c_check_status(struct gpu_i2c_dev *i2cd)
  76 {
  77         unsigned long target = jiffies + msecs_to_jiffies(1000);
  78         u32 val;
  79
  80         do {
  81                 val = readl(i2cd->regs + I2C_MST_CNTL);
  82                 if (!(val & I2C_MST_CNTL_CYCLE_TRIGGER))
  83                         break;
  84                 if ((val & I2C_MST_CNTL_STATUS) !=
  85                                 I2C_MST_CNTL_STATUS_BUS_BUSY)
  86                         break;
  87                 usleep_range(500, 600);
  88         } while (time_is_after_jiffies(target));
  89
  90         if (time_is_before_jiffies(target)) {
  91                 dev_err(i2cd->dev, "i2c timeout error %x\n", val);
  92                 return -ETIME;
  93         }
  94
  95         val = readl(i2cd->regs + I2C_MST_CNTL);
  96         switch (val & I2C_MST_CNTL_STATUS) {
  97         case I2C_MST_CNTL_STATUS_OKAY:
  98                 return 0;
  99         case I2C_MST_CNTL_STATUS_NO_ACK:
 100                 return -EIO;
 101         case I2C_MST_CNTL_STATUS_TIMEOUT:
 102                 return -ETIME;
 103         default:
 104                 return 0;
 105         }
 106 }
 107
 108 static int gpu_i2c_read(struct gpu_i2c_dev *i2cd, u8 *data, u16 len)
 109 {
 110         int status;
 111         u32 val;
 112
 113         val = I2C_MST_CNTL_GEN_START | I2C_MST_CNTL_CMD_READ |
 114                 (len << I2C_MST_CNTL_BURST_SIZE_SHIFT) |
 115                 I2C_MST_CNTL_CYCLE_TRIGGER | I2C_MST_CNTL_GEN_NACK;
 116         writel(val, i2cd->regs + I2C_MST_CNTL);
 117
 118         status = gpu_i2c_check_status(i2cd);
 119         if (status < 0)
 120                 return status;
 121
 122         val = readl(i2cd->regs + I2C_MST_DATA);
 123         switch (len) {
 124         case 1:
 125                 data[0] = val;
 126                 break;
 127         case 2:
 128                 put_unaligned_be16(val, data);
 129                 break;
 130         case 3:
 131                 put_unaligned_be16(val >> 8, data);
 132                 data[2] = val;
 133                 break;
 134         case 4:
 135                 put_unaligned_be32(val, data);
 136                 break;
 137         default:
 138                 break;
 139         }
 140         return status;
 141 }
 142
 143 static int gpu_i2c_start(struct gpu_i2c_dev *i2cd)
 144 {
 145         writel(I2C_MST_CNTL_GEN_START, i2cd->regs + I2C_MST_CNTL);
 146         return gpu_i2c_check_status(i2cd);
 147 }
 148
 149 static int gpu_i2c_stop(struct gpu_i2c_dev *i2cd)
 150 {
 151         writel(I2C_MST_CNTL_GEN_STOP, i2cd->regs + I2C_MST_CNTL);
 152         return gpu_i2c_check_status(i2cd);
 153 }
 154
 155 static int gpu_i2c_write(struct gpu_i2c_dev *i2cd, u8 data)
 156 {
 157         u32 val;
 158
 159         writel(data, i2cd->regs + I2C_MST_DATA);
 160
 161         val = I2C_MST_CNTL_CMD_WRITE | (1 << I2C_MST_CNTL_BURST_SIZE_SHIFT);
 162         writel(val, i2cd->regs + I2C_MST_CNTL);
 163
 164         return gpu_i2c_check_status(i2cd);
 165 }
 166
 167 static int gpu_i2c_master_xfer(struct i2c_adapter *adap,
 168                                struct i2c_msg *msgs, int num)
 169 {
 170         struct gpu_i2c_dev *i2cd = i2c_get_adapdata(adap);
 171         int status, status2;
 172         int i, j;
 173
 174         /*
 175          * The controller supports maximum 4 byte read due to known
 176          * limitation of sending STOP after every read.
 177          */
 178         for (i = 0; i < num; i++) {
 179                 if (msgs[i].flags & I2C_M_RD) {
 180                         /* program client address before starting read */
 181                         writel(msgs[i].addr, i2cd->regs + I2C_MST_ADDR);
 182                         /* gpu_i2c_read has implicit start */
 183                         status = gpu_i2c_read(i2cd, msgs[i].buf, msgs[i].len);
 184                         if (status < 0)
 185                                 goto stop;
 186                 } else {
 187                         u8 addr = i2c_8bit_addr_from_msg(msgs + i);
 188
 189                         status = gpu_i2c_start(i2cd);
 190                         if (status < 0) {
 191                                 if (i == 0)
 192                                         return status;
 193                                 goto stop;
 194                         }
 195
 196                         status = gpu_i2c_write(i2cd, addr);
 197                         if (status < 0)
 198                                 goto stop;
 199
 200                         for (j = 0; j < msgs[i].len; j++) {
 201                                 status = gpu_i2c_write(i2cd, msgs[i].buf[j]);
 202                                 if (status < 0)
 203                                         goto stop;
 204                         }
 205                 }
 206         }
 207         status = gpu_i2c_stop(i2cd);
 208         if (status < 0)
 209                 return status;
 210
 211         return i;
 212 stop:
 213         status2 = gpu_i2c_stop(i2cd);
 214         if (status2 < 0)
 215                 dev_err(i2cd->dev, "i2c stop failed %d\n", status2);
 216         return status;
 217 }
 218
 219 static const struct i2c_adapter_quirks gpu_i2c_quirks = {
 220         .max_read_len = 4,
 221         .flags = I2C_AQ_COMB_WRITE_THEN_READ,
 222 };
 223
 224 static u32 gpu_i2c_functionality(struct i2c_adapter *adap)
 225 {
 226         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 227 }
 228
 229 static const struct i2c_algorithm gpu_i2c_algorithm = {
 230         .master_xfer    = gpu_i2c_master_xfer,
 231         .functionality  = gpu_i2c_functionality,
 232 };
 233
 234 /*
 235  * This driver is for Nvidia GPU cards with USB Type-C interface.
 236  * We want to identify the cards using vendor ID and class code only
 237  * to avoid dependency of adding product id for any new card which
 238  * requires this driver.
 239  * Currently there is no class code defined for UCSI device over PCI
 240  * so using UNKNOWN class for now and it will be updated when UCSI
 241  * over PCI gets a class code.
 242  * There is no other NVIDIA cards with UNKNOWN class code. Even if the
 243  * driver gets loaded for an undesired card then eventually i2c_read()
 244  * (initiated from UCSI i2c_client) will timeout or UCSI commands will
 245  * timeout.
 246  */
 247 #define PCI_CLASS_SERIAL_UNKNOWN        0x0c80
 248 static const struct pci_device_id gpu_i2c_ids[] = {
 249         { PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
 250                 PCI_CLASS_SERIAL_UNKNOWN << 8, 0xffffff00},
 251         { }
 252 };
 253 MODULE_DEVICE_TABLE(pci, gpu_i2c_ids);
 254
 255 static int gpu_populate_client(struct gpu_i2c_dev *i2cd, int irq)
 256 {
 257         struct i2c_client *ccgx_client;
 258
 259         i2cd->gpu_ccgx_ucsi = devm_kzalloc(i2cd->dev,
 260                                            sizeof(*i2cd->gpu_ccgx_ucsi),
 261                                            GFP_KERNEL);
 262         if (!i2cd->gpu_ccgx_ucsi)
 263                 return -ENOMEM;
 264
 265         strlcpy(i2cd->gpu_ccgx_ucsi->type, "ccgx-ucsi",
 266                 sizeof(i2cd->gpu_ccgx_ucsi->type));
 267         i2cd->gpu_ccgx_ucsi->addr = 0x8;
 268         i2cd->gpu_ccgx_ucsi->irq = irq;
 269         ccgx_client = i2c_new_device(&i2cd->adapter, i2cd->gpu_ccgx_ucsi);
 270         if (!ccgx_client)
 271                 return -ENODEV;
 272
 273         return 0;
 274 }
 275
 276 static int gpu_i2c_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 277 {
 278         struct gpu_i2c_dev *i2cd;
 279         int status;
 280
 281         i2cd = devm_kzalloc(&pdev->dev, sizeof(*i2cd), GFP_KERNEL);
 282         if (!i2cd)
 283                 return -ENOMEM;
 284
 285         i2cd->dev = &pdev->dev;
 286         dev_set_drvdata(&pdev->dev, i2cd);
 287
 288         status = pcim_enable_device(pdev);
 289         if (status < 0) {
 290                 dev_err(&pdev->dev, "pcim_enable_device failed %d\n", status);
 291                 return status;
 292         }
 293
 294         pci_set_master(pdev);
 295
 296         i2cd->regs = pcim_iomap(pdev, 0, 0);
 297         if (!i2cd->regs) {
 298                 dev_err(&pdev->dev, "pcim_iomap failed\n");
 299                 return -ENOMEM;
 300         }
 301
 302         status = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSI);
 303         if (status < 0) {
 304                 dev_err(&pdev->dev, "pci_alloc_irq_vectors err %d\n", status);
 305                 return status;
 306         }
 307
 308         gpu_enable_i2c_bus(i2cd);
 309
 310         i2c_set_adapdata(&i2cd->adapter, i2cd);
 311         i2cd->adapter.owner = THIS_MODULE;
 312         strlcpy(i2cd->adapter.name, "NVIDIA GPU I2C adapter",
 313                 sizeof(i2cd->adapter.name));
 314         i2cd->adapter.algo = &gpu_i2c_algorithm;
 315         i2cd->adapter.quirks = &gpu_i2c_quirks;
 316         i2cd->adapter.dev.parent = &pdev->dev;
 317         status = i2c_add_adapter(&i2cd->adapter);
 318         if (status < 0)
 319                 goto free_irq_vectors;
 320
 321         status = gpu_populate_client(i2cd, pdev->irq);
 322         if (status < 0) {
 323                 dev_err(&pdev->dev, "gpu_populate_client failed %d\n", status);
 324                 goto del_adapter;
 325         }
 326
 327         return 0;
 328
 329 del_adapter:
 330         i2c_del_adapter(&i2cd->adapter);
 331 free_irq_vectors:
 332         pci_free_irq_vectors(pdev);
 333         return status;
 334 }
 335
 336 static void gpu_i2c_remove(struct pci_dev *pdev)
 337 {
 338         struct gpu_i2c_dev *i2cd = dev_get_drvdata(&pdev->dev);
 339
 340         i2c_del_adapter(&i2cd->adapter);
 341         pci_free_irq_vectors(pdev);
 342 }
 343
 344 static int gpu_i2c_resume(struct device *dev)
 345 {
 346         struct gpu_i2c_dev *i2cd = dev_get_drvdata(dev);
 347
 348         gpu_enable_i2c_bus(i2cd);
 349         return 0;
 350 }
 351
 352 static UNIVERSAL_DEV_PM_OPS(gpu_i2c_driver_pm, NULL, gpu_i2c_resume, NULL);
 353
 354 static struct pci_driver gpu_i2c_driver = {
 355         .name           = "nvidia-gpu",
 356         .id_table       = gpu_i2c_ids,
 357         .probe          = gpu_i2c_probe,
 358         .remove         = gpu_i2c_remove,
 359         .driver         = {
 360                 .pm     = &gpu_i2c_driver_pm,
 361         },
 362 };
 363
 364 module_pci_driver(gpu_i2c_driver);
 365
 366 MODULE_AUTHOR("Ajay Gupta <ajayg@nvidia.com>");
 367 MODULE_DESCRIPTION("Nvidia GPU I2C controller Driver");
 368 MODULE_LICENSE("GPL v2");