drivers/hwmon/occ/p8_i2c.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 // Copyright IBM Corp 2019
   3
   4 #include <linux/device.h>
   5 #include <linux/errno.h>
   6 #include <linux/fsi-occ.h>
   7 #include <linux/i2c.h>
   8 #include <linux/jiffies.h>
   9 #include <linux/module.h>
  10 #include <linux/sched.h>
  11 #include <asm/unaligned.h>
  12
  13 #include "common.h"
  14
  15 #define OCC_TIMEOUT_MS                  1000
  16 #define OCC_CMD_IN_PRG_WAIT_MS          50
  17
  18 /* OCB (on-chip control bridge - interface to OCC) registers */
  19 #define OCB_DATA1                       0x6B035
  20 #define OCB_ADDR                        0x6B070
  21 #define OCB_DATA3                       0x6B075
  22
  23 /* OCC SRAM address space */
  24 #define OCC_SRAM_ADDR_CMD               0xFFFF6000
  25 #define OCC_SRAM_ADDR_RESP              0xFFFF7000
  26
  27 #define OCC_DATA_ATTN                   0x20010000
  28
  29 struct p8_i2c_occ {
  30         struct occ occ;
  31         struct i2c_client *client;
  32 };
  33
  34 #define to_p8_i2c_occ(x)        container_of((x), struct p8_i2c_occ, occ)
  35
  36 static int p8_i2c_occ_getscom(struct i2c_client *client, u32 address, u8 *data)
  37 {
  38         ssize_t rc;
  39         __be64 buf;
  40         struct i2c_msg msgs[2];
  41
  42         /* p8 i2c slave requires shift */
  43         address <<= 1;
  44
  45         msgs[0].addr = client->addr;
  46         msgs[0].flags = client->flags & I2C_M_TEN;
  47         msgs[0].len = sizeof(u32);
  48         /* address is a scom address; bus-endian */
  49         msgs[0].buf = (char *)&address;
  50
  51         /* data from OCC is big-endian */
  52         msgs[1].addr = client->addr;
  53         msgs[1].flags = (client->flags & I2C_M_TEN) | I2C_M_RD;
  54         msgs[1].len = sizeof(u64);
  55         msgs[1].buf = (char *)&buf;
  56
  57         rc = i2c_transfer(client->adapter, msgs, 2);
  58         if (rc < 0)
  59                 return rc;
  60
  61         *(u64 *)data = be64_to_cpu(buf);
  62
  63         return 0;
  64 }
  65
  66 static int p8_i2c_occ_putscom(struct i2c_client *client, u32 address, u8 *data)
  67 {
  68         u32 buf[3];
  69         ssize_t rc;
  70
  71         /* p8 i2c slave requires shift */
  72         address <<= 1;
  73
  74         /* address is bus-endian; data passed through from user as-is */
  75         buf[0] = address;
  76         memcpy(&buf[1], &data[4], sizeof(u32));
  77         memcpy(&buf[2], data, sizeof(u32));
  78
  79         rc = i2c_master_send(client, (const char *)buf, sizeof(buf));
  80         if (rc < 0)
  81                 return rc;
  82         else if (rc != sizeof(buf))
  83                 return -EIO;
  84
  85         return 0;
  86 }
  87
  88 static int p8_i2c_occ_putscom_u32(struct i2c_client *client, u32 address,
  89                                   u32 data0, u32 data1)
  90 {
  91         u8 buf[8];
  92
  93         memcpy(buf, &data0, 4);
  94         memcpy(buf + 4, &data1, 4);
  95
  96         return p8_i2c_occ_putscom(client, address, buf);
  97 }
  98
  99 static int p8_i2c_occ_putscom_be(struct i2c_client *client, u32 address,
 100                                  u8 *data, size_t len)
 101 {
 102         __be32 data0 = 0, data1 = 0;
 103
 104         memcpy(&data0, data, min_t(size_t, len, 4));
 105         if (len > 4) {
 106                 len -= 4;
 107                 memcpy(&data1, data + 4, min_t(size_t, len, 4));
 108         }
 109
 110         return p8_i2c_occ_putscom_u32(client, address, be32_to_cpu(data0),
 111                                       be32_to_cpu(data1));
 112 }
 113
 114 static int p8_i2c_occ_send_cmd(struct occ *occ, u8 *cmd, size_t len,
 115                                void *resp, size_t resp_len)
 116 {
 117         int i, rc;
 118         unsigned long start;
 119         u16 data_length;
 120         const unsigned long timeout = msecs_to_jiffies(OCC_TIMEOUT_MS);
 121         const long wait_time = msecs_to_jiffies(OCC_CMD_IN_PRG_WAIT_MS);
 122         struct p8_i2c_occ *ctx = to_p8_i2c_occ(occ);
 123         struct i2c_client *client = ctx->client;
 124         struct occ_response *or = (struct occ_response *)resp;
 125
 126         start = jiffies;
 127
 128         /* set sram address for command */
 129         rc = p8_i2c_occ_putscom_u32(client, OCB_ADDR, OCC_SRAM_ADDR_CMD, 0);
 130         if (rc)
 131                 return rc;
 132
 133         /* write command (expected to already be BE), we need bus-endian... */
 134         rc = p8_i2c_occ_putscom_be(client, OCB_DATA3, cmd, len);
 135         if (rc)
 136                 return rc;
 137
 138         /* trigger OCC attention */
 139         rc = p8_i2c_occ_putscom_u32(client, OCB_DATA1, OCC_DATA_ATTN, 0);
 140         if (rc)
 141                 return rc;
 142
 143         do {
 144                 /* set sram address for response */
 145                 rc = p8_i2c_occ_putscom_u32(client, OCB_ADDR,
 146                                             OCC_SRAM_ADDR_RESP, 0);
 147                 if (rc)
 148                         return rc;
 149
 150                 rc = p8_i2c_occ_getscom(client, OCB_DATA3, (u8 *)resp);
 151                 if (rc)
 152                         return rc;
 153
 154                 /* wait for OCC */
 155                 if (or->return_status == OCC_RESP_CMD_IN_PRG) {
 156                         rc = -EALREADY;
 157
 158                         if (time_after(jiffies, start + timeout))
 159                                 break;
 160
 161                         set_current_state(TASK_INTERRUPTIBLE);
 162                         schedule_timeout(wait_time);
 163                 }
 164         } while (rc);
 165
 166         /* check the OCC response */
 167         switch (or->return_status) {
 168         case OCC_RESP_CMD_IN_PRG:
 169                 rc = -ETIMEDOUT;
 170                 break;
 171         case OCC_RESP_SUCCESS:
 172                 rc = 0;
 173                 break;
 174         case OCC_RESP_CMD_INVAL:
 175         case OCC_RESP_CMD_LEN_INVAL:
 176         case OCC_RESP_DATA_INVAL:
 177         case OCC_RESP_CHKSUM_ERR:
 178                 rc = -EINVAL;
 179                 break;
 180         case OCC_RESP_INT_ERR:
 181         case OCC_RESP_BAD_STATE:
 182         case OCC_RESP_CRIT_EXCEPT:
 183         case OCC_RESP_CRIT_INIT:
 184         case OCC_RESP_CRIT_WATCHDOG:
 185         case OCC_RESP_CRIT_OCB:
 186         case OCC_RESP_CRIT_HW:
 187                 rc = -EREMOTEIO;
 188                 break;
 189         default:
 190                 rc = -EPROTO;
 191         }
 192
 193         if (rc < 0)
 194                 return rc;
 195
 196         data_length = get_unaligned_be16(&or->data_length);
 197         if ((data_length + 7) > resp_len)
 198                 return -EMSGSIZE;
 199
 200         /* fetch the rest of the response data */
 201         for (i = 8; i < data_length + 7; i += 8) {
 202                 rc = p8_i2c_occ_getscom(client, OCB_DATA3, ((u8 *)resp) + i);
 203                 if (rc)
 204                         return rc;
 205         }
 206
 207         return 0;
 208 }
 209
 210 static int p8_i2c_occ_probe(struct i2c_client *client)
 211 {
 212         struct occ *occ;
 213         struct p8_i2c_occ *ctx = devm_kzalloc(&client->dev, sizeof(*ctx),
 214                                               GFP_KERNEL);
 215         if (!ctx)
 216                 return -ENOMEM;
 217
 218         ctx->client = client;
 219         occ = &ctx->occ;
 220         occ->bus_dev = &client->dev;
 221         dev_set_drvdata(&client->dev, occ);
 222
 223         occ->powr_sample_time_us = 250;
 224         occ->poll_cmd_data = 0x10;              /* P8 OCC poll data */
 225         occ->send_cmd = p8_i2c_occ_send_cmd;
 226
 227         return occ_setup(occ);
 228 }
 229
 230 static void p8_i2c_occ_remove(struct i2c_client *client)
 231 {
 232         struct occ *occ = dev_get_drvdata(&client->dev);
 233
 234         occ_shutdown(occ);
 235 }
 236
 237 static const struct of_device_id p8_i2c_occ_of_match[] = {
 238         { .compatible = "ibm,p8-occ-hwmon" },
 239         {}
 240 };
 241 MODULE_DEVICE_TABLE(of, p8_i2c_occ_of_match);
 242
 243 static struct i2c_driver p8_i2c_occ_driver = {
 244         .class = I2C_CLASS_HWMON,
 245         .driver = {
 246                 .name = "occ-hwmon",
 247                 .of_match_table = p8_i2c_occ_of_match,
 248         },
 249         .probe = p8_i2c_occ_probe,
 250         .remove = p8_i2c_occ_remove,
 251 };
 252
 253 module_i2c_driver(p8_i2c_occ_driver);
 254
 255 MODULE_AUTHOR("Eddie James <eajames@linux.ibm.com>");
 256 MODULE_DESCRIPTION("BMC P8 OCC hwmon driver");
 257 MODULE_LICENSE("GPL");