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/iopoll.h>
  12 #include <linux/module.h>
  13 #include <linux/pci.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/pm.h>
  16 #include <linux/pm_runtime.h>
  17 #include <linux/power_supply.h>
  18
  19 #include <linux/unaligned.h>
  20
  21 #include "i2c-ccgx-ucsi.h"
  22
  23 /* I2C definitions */
  24 #define I2C_MST_CNTL                            0x00
  25 #define I2C_MST_CNTL_GEN_START                  BIT(0)
  26 #define I2C_MST_CNTL_GEN_STOP                   BIT(1)
  27 #define I2C_MST_CNTL_CMD_READ                   (1 << 2)
  28 #define I2C_MST_CNTL_CMD_WRITE                  (2 << 2)
  29 #define I2C_MST_CNTL_BURST_SIZE_SHIFT           6
  30 #define I2C_MST_CNTL_GEN_NACK                   BIT(28)
  31 #define I2C_MST_CNTL_STATUS                     GENMASK(30, 29)
  32 #define I2C_MST_CNTL_STATUS_OKAY                (0 << 29)
  33 #define I2C_MST_CNTL_STATUS_NO_ACK              (1 << 29)
  34 #define I2C_MST_CNTL_STATUS_TIMEOUT             (2 << 29)
  35 #define I2C_MST_CNTL_STATUS_BUS_BUSY            (3 << 29)
  36 #define I2C_MST_CNTL_CYCLE_TRIGGER              BIT(31)
  37
  38 #define I2C_MST_ADDR                            0x04
  39
  40 #define I2C_MST_I2C0_TIMING                             0x08
  41 #define I2C_MST_I2C0_TIMING_SCL_PERIOD_100KHZ           0x10e
  42 #define I2C_MST_I2C0_TIMING_TIMEOUT_CLK_CNT             16
  43 #define I2C_MST_I2C0_TIMING_TIMEOUT_CLK_CNT_MAX         255
  44 #define I2C_MST_I2C0_TIMING_TIMEOUT_CHECK               BIT(24)
  45
  46 #define I2C_MST_DATA                                    0x0c
  47
  48 #define I2C_MST_HYBRID_PADCTL                           0x20
  49 #define I2C_MST_HYBRID_PADCTL_MODE_I2C                  BIT(0)
  50 #define I2C_MST_HYBRID_PADCTL_I2C_SCL_INPUT_RCV         BIT(14)
  51 #define I2C_MST_HYBRID_PADCTL_I2C_SDA_INPUT_RCV         BIT(15)
  52
  53 struct gpu_i2c_dev {
  54         struct device *dev;
  55         void __iomem *regs;
  56         struct i2c_adapter adapter;
  57         struct i2c_board_info *gpu_ccgx_ucsi;
  58         struct i2c_client *ccgx_client;
  59 };
  60
  61 static void gpu_enable_i2c_bus(struct gpu_i2c_dev *i2cd)
  62 {
  63         u32 val;
  64
  65         /* enable I2C */
  66         val = readl(i2cd->regs + I2C_MST_HYBRID_PADCTL);
  67         val |= I2C_MST_HYBRID_PADCTL_MODE_I2C |
  68                 I2C_MST_HYBRID_PADCTL_I2C_SCL_INPUT_RCV |
  69                 I2C_MST_HYBRID_PADCTL_I2C_SDA_INPUT_RCV;
  70         writel(val, i2cd->regs + I2C_MST_HYBRID_PADCTL);
  71
  72         /* enable 100KHZ mode */
  73         val = I2C_MST_I2C0_TIMING_SCL_PERIOD_100KHZ;
  74         val |= (I2C_MST_I2C0_TIMING_TIMEOUT_CLK_CNT_MAX
  75             << I2C_MST_I2C0_TIMING_TIMEOUT_CLK_CNT);
  76         val |= I2C_MST_I2C0_TIMING_TIMEOUT_CHECK;
  77         writel(val, i2cd->regs + I2C_MST_I2C0_TIMING);
  78 }
  79
  80 static int gpu_i2c_check_status(struct gpu_i2c_dev *i2cd)
  81 {
  82         u32 val;
  83         int ret;
  84
  85         ret = readl_poll_timeout(i2cd->regs + I2C_MST_CNTL, val,
  86                                  !(val & I2C_MST_CNTL_CYCLE_TRIGGER) ||
  87                                  (val & I2C_MST_CNTL_STATUS) != I2C_MST_CNTL_STATUS_BUS_BUSY,
  88                                  500, 1000 * USEC_PER_MSEC);
  89
  90         if (ret) {
  91                 dev_err(i2cd->dev, "i2c timeout error %x\n", val);
  92                 return -ETIMEDOUT;
  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 -ENXIO;
 101         case I2C_MST_CNTL_STATUS_TIMEOUT:
 102                 return -ETIMEDOUT;
 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_be24(val, data);
 132                 break;
 133         case 4:
 134                 put_unaligned_be32(val, data);
 135                 break;
 136         default:
 137                 break;
 138         }
 139         return status;
 140 }
 141
 142 static int gpu_i2c_start(struct gpu_i2c_dev *i2cd)
 143 {
 144         writel(I2C_MST_CNTL_GEN_START, i2cd->regs + I2C_MST_CNTL);
 145         return gpu_i2c_check_status(i2cd);
 146 }
 147
 148 static int gpu_i2c_stop(struct gpu_i2c_dev *i2cd)
 149 {
 150         writel(I2C_MST_CNTL_GEN_STOP, i2cd->regs + I2C_MST_CNTL);
 151         return gpu_i2c_check_status(i2cd);
 152 }
 153
 154 static int gpu_i2c_write(struct gpu_i2c_dev *i2cd, u8 data)
 155 {
 156         u32 val;
 157
 158         writel(data, i2cd->regs + I2C_MST_DATA);
 159
 160         val = I2C_MST_CNTL_CMD_WRITE | (1 << I2C_MST_CNTL_BURST_SIZE_SHIFT);
 161         writel(val, i2cd->regs + I2C_MST_CNTL);
 162
 163         return gpu_i2c_check_status(i2cd);
 164 }
 165
 166 static int gpu_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 167 {
 168         struct gpu_i2c_dev *i2cd = i2c_get_adapdata(adap);
 169         int status, status2;
 170         bool send_stop = true;
 171         int i, j;
 172
 173         /*
 174          * The controller supports maximum 4 byte read due to known
 175          * limitation of sending STOP after every read.
 176          */
 177         pm_runtime_get_sync(i2cd->dev);
 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 exit;
 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                                         send_stop = false;
 193                                 goto exit;
 194                         }
 195
 196                         status = gpu_i2c_write(i2cd, addr);
 197                         if (status < 0)
 198                                 goto exit;
 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 exit;
 204                         }
 205                 }
 206         }
 207         send_stop = false;
 208         status = gpu_i2c_stop(i2cd);
 209         if (status < 0)
 210                 goto exit;
 211
 212         status = i;
 213 exit:
 214         if (send_stop) {
 215                 status2 = gpu_i2c_stop(i2cd);
 216                 if (status2 < 0)
 217                         dev_err(i2cd->dev, "i2c stop failed %d\n", status2);
 218         }
 219         pm_runtime_mark_last_busy(i2cd->dev);
 220         pm_runtime_put_autosuspend(i2cd->dev);
 221         return status;
 222 }
 223
 224 static const struct i2c_adapter_quirks gpu_i2c_quirks = {
 225         .max_read_len = 4,
 226         .max_comb_2nd_msg_len = 4,
 227         .flags = I2C_AQ_COMB_WRITE_THEN_READ,
 228 };
 229
 230 static u32 gpu_i2c_functionality(struct i2c_adapter *adap)
 231 {
 232         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 233 }
 234
 235 static const struct i2c_algorithm gpu_i2c_algorithm = {
 236         .xfer = gpu_i2c_xfer,
 237         .functionality = gpu_i2c_functionality,
 238 };
 239
 240 /*
 241  * This driver is for Nvidia GPU cards with USB Type-C interface.
 242  * We want to identify the cards using vendor ID and class code only
 243  * to avoid dependency of adding product id for any new card which
 244  * requires this driver.
 245  * Currently there is no class code defined for UCSI device over PCI
 246  * so using UNKNOWN class for now and it will be updated when UCSI
 247  * over PCI gets a class code.
 248  * There is no other NVIDIA cards with UNKNOWN class code. Even if the
 249  * driver gets loaded for an undesired card then eventually i2c_read()
 250  * (initiated from UCSI i2c_client) will timeout or UCSI commands will
 251  * timeout.
 252  */
 253 #define PCI_CLASS_SERIAL_UNKNOWN        0x0c80
 254 static const struct pci_device_id gpu_i2c_ids[] = {
 255         { PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
 256                 PCI_CLASS_SERIAL_UNKNOWN << 8, 0xffffff00},
 257         { }
 258 };
 259 MODULE_DEVICE_TABLE(pci, gpu_i2c_ids);
 260
 261 static const struct property_entry ccgx_props[] = {
 262         /* Use FW built for NVIDIA GPU only */
 263         PROPERTY_ENTRY_STRING("firmware-name", "nvidia,gpu"),
 264         /* USB-C doesn't power the system */
 265         PROPERTY_ENTRY_U8("scope", POWER_SUPPLY_SCOPE_DEVICE),
 266         { }
 267 };
 268
 269 static const struct software_node ccgx_node = {
 270         .properties = ccgx_props,
 271 };
 272
 273 static int gpu_i2c_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 274 {
 275         struct device *dev = &pdev->dev;
 276         struct gpu_i2c_dev *i2cd;
 277         int status;
 278
 279         i2cd = devm_kzalloc(dev, sizeof(*i2cd), GFP_KERNEL);
 280         if (!i2cd)
 281                 return -ENOMEM;
 282
 283         i2cd->dev = dev;
 284         dev_set_drvdata(dev, i2cd);
 285
 286         status = pcim_enable_device(pdev);
 287         if (status < 0)
 288                 return dev_err_probe(dev, status, "pcim_enable_device failed\n");
 289
 290         pci_set_master(pdev);
 291
 292         i2cd->regs = pcim_iomap(pdev, 0, 0);
 293         if (!i2cd->regs)
 294                 return dev_err_probe(dev, -ENOMEM, "pcim_iomap failed\n");
 295
 296         status = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSI);
 297         if (status < 0)
 298                 return dev_err_probe(dev, status, "pci_alloc_irq_vectors err\n");
 299
 300         gpu_enable_i2c_bus(i2cd);
 301
 302         i2c_set_adapdata(&i2cd->adapter, i2cd);
 303         i2cd->adapter.owner = THIS_MODULE;
 304         strscpy(i2cd->adapter.name, "NVIDIA GPU I2C adapter",
 305                 sizeof(i2cd->adapter.name));
 306         i2cd->adapter.algo = &gpu_i2c_algorithm;
 307         i2cd->adapter.quirks = &gpu_i2c_quirks;
 308         i2cd->adapter.dev.parent = dev;
 309         status = i2c_add_adapter(&i2cd->adapter);
 310         if (status < 0)
 311                 goto free_irq_vectors;
 312
 313         i2cd->ccgx_client = i2c_new_ccgx_ucsi(&i2cd->adapter, pdev->irq, &ccgx_node);
 314         if (IS_ERR(i2cd->ccgx_client)) {
 315                 status = dev_err_probe(dev, PTR_ERR(i2cd->ccgx_client), "register UCSI failed\n");
 316                 goto del_adapter;
 317         }
 318
 319         pm_runtime_set_autosuspend_delay(dev, 3000);
 320         pm_runtime_use_autosuspend(dev);
 321         pm_runtime_put_autosuspend(dev);
 322         pm_runtime_allow(dev);
 323
 324         return 0;
 325
 326 del_adapter:
 327         i2c_del_adapter(&i2cd->adapter);
 328 free_irq_vectors:
 329         pci_free_irq_vectors(pdev);
 330         return status;
 331 }
 332
 333 static void gpu_i2c_remove(struct pci_dev *pdev)
 334 {
 335         struct gpu_i2c_dev *i2cd = pci_get_drvdata(pdev);
 336
 337         pm_runtime_get_noresume(i2cd->dev);
 338         i2c_del_adapter(&i2cd->adapter);
 339         pci_free_irq_vectors(pdev);
 340 }
 341
 342 #define gpu_i2c_suspend NULL
 343
 344 static __maybe_unused 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         /*
 350          * Runtime resume ccgx client so that it can see for any
 351          * connector change event. Old ccg firmware has known
 352          * issue of not triggering interrupt when a device is
 353          * connected to runtime resume the controller.
 354          */
 355         pm_request_resume(&i2cd->ccgx_client->dev);
 356         return 0;
 357 }
 358
 359 static UNIVERSAL_DEV_PM_OPS(gpu_i2c_driver_pm, gpu_i2c_suspend, gpu_i2c_resume,
 360                             NULL);
 361
 362 static struct pci_driver gpu_i2c_driver = {
 363         .name           = "nvidia-gpu",
 364         .id_table       = gpu_i2c_ids,
 365         .probe          = gpu_i2c_probe,
 366         .remove         = gpu_i2c_remove,
 367         .driver         = {
 368                 .pm     = &gpu_i2c_driver_pm,
 369         },
 370 };
 371
 372 module_pci_driver(gpu_i2c_driver);
 373
 374 MODULE_AUTHOR("Ajay Gupta <ajayg@nvidia.com>");
 375 MODULE_DESCRIPTION("Nvidia GPU I2C controller Driver");
 376 MODULE_LICENSE("GPL v2");