kernel/drivers/char/tpm/st33zp24/i2c.c

   1 /*
   2  * STMicroelectronics TPM I2C Linux driver for TPM ST33ZP24
   3  * Copyright (C) 2009 - 2015 STMicroelectronics
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include <linux/module.h>
  20 #include <linux/i2c.h>
  21 #include <linux/gpio.h>
  22 #include <linux/of_irq.h>
  23 #include <linux/of_gpio.h>
  24 #include <linux/tpm.h>
  25 #include <linux/platform_data/st33zp24.h>
  26
  27 #include "st33zp24.h"
  28
  29 #define TPM_DUMMY_BYTE                  0xAA
  30
  31 struct st33zp24_i2c_phy {
  32         struct i2c_client *client;
  33         u8 buf[TPM_BUFSIZE + 1];
  34         int io_lpcpd;
  35 };
  36
  37 /*
  38  * write8_reg
  39  * Send byte to the TIS register according to the ST33ZP24 I2C protocol.
  40  * @param: tpm_register, the tpm tis register where the data should be written
  41  * @param: tpm_data, the tpm_data to write inside the tpm_register
  42  * @param: tpm_size, The length of the data
  43  * @return: Returns negative errno, or else the number of bytes written.
  44  */
  45 static int write8_reg(void *phy_id, u8 tpm_register, u8 *tpm_data, int tpm_size)
  46 {
  47         struct st33zp24_i2c_phy *phy = phy_id;
  48
  49         phy->buf[0] = tpm_register;
  50         memcpy(phy->buf + 1, tpm_data, tpm_size);
  51         return i2c_master_send(phy->client, phy->buf, tpm_size + 1);
  52 } /* write8_reg() */
  53
  54 /*
  55  * read8_reg
  56  * Recv byte from the TIS register according to the ST33ZP24 I2C protocol.
  57  * @param: tpm_register, the tpm tis register where the data should be read
  58  * @param: tpm_data, the TPM response
  59  * @param: tpm_size, tpm TPM response size to read.
  60  * @return: number of byte read successfully: should be one if success.
  61  */
  62 static int read8_reg(void *phy_id, u8 tpm_register, u8 *tpm_data, int tpm_size)
  63 {
  64         struct st33zp24_i2c_phy *phy = phy_id;
  65         u8 status = 0;
  66         u8 data;
  67
  68         data = TPM_DUMMY_BYTE;
  69         status = write8_reg(phy, tpm_register, &data, 1);
  70         if (status == 2)
  71                 status = i2c_master_recv(phy->client, tpm_data, tpm_size);
  72         return status;
  73 } /* read8_reg() */
  74
  75 /*
  76  * st33zp24_i2c_send
  77  * Send byte to the TIS register according to the ST33ZP24 I2C protocol.
  78  * @param: phy_id, the phy description
  79  * @param: tpm_register, the tpm tis register where the data should be written
  80  * @param: tpm_data, the tpm_data to write inside the tpm_register
  81  * @param: tpm_size, the length of the data
  82  * @return: number of byte written successfully: should be one if success.
  83  */
  84 static int st33zp24_i2c_send(void *phy_id, u8 tpm_register, u8 *tpm_data,
  85                              int tpm_size)
  86 {
  87         return write8_reg(phy_id, tpm_register | TPM_WRITE_DIRECTION, tpm_data,
  88                           tpm_size);
  89 }
  90
  91 /*
  92  * st33zp24_i2c_recv
  93  * Recv byte from the TIS register according to the ST33ZP24 I2C protocol.
  94  * @param: phy_id, the phy description
  95  * @param: tpm_register, the tpm tis register where the data should be read
  96  * @param: tpm_data, the TPM response
  97  * @param: tpm_size, tpm TPM response size to read.
  98  * @return: number of byte read successfully: should be one if success.
  99  */
 100 static int st33zp24_i2c_recv(void *phy_id, u8 tpm_register, u8 *tpm_data,
 101                              int tpm_size)
 102 {
 103         return read8_reg(phy_id, tpm_register, tpm_data, tpm_size);
 104 }
 105
 106 static const struct st33zp24_phy_ops i2c_phy_ops = {
 107         .send = st33zp24_i2c_send,
 108         .recv = st33zp24_i2c_recv,
 109 };
 110
 111 #ifdef CONFIG_OF
 112 static int st33zp24_i2c_of_request_resources(struct st33zp24_i2c_phy *phy)
 113 {
 114         struct device_node *pp;
 115         struct i2c_client *client = phy->client;
 116         int gpio;
 117         int ret;
 118
 119         pp = client->dev.of_node;
 120         if (!pp) {
 121                 dev_err(&client->dev, "No platform data\n");
 122                 return -ENODEV;
 123         }
 124
 125         /* Get GPIO from device tree */
 126         gpio = of_get_named_gpio(pp, "lpcpd-gpios", 0);
 127         if (gpio < 0) {
 128                 dev_err(&client->dev,
 129                         "Failed to retrieve lpcpd-gpios from dts.\n");
 130                 phy->io_lpcpd = -1;
 131                 /*
 132                  * lpcpd pin is not specified. This is not an issue as
 133                  * power management can be also managed by TPM specific
 134                  * commands. So leave with a success status code.
 135                  */
 136                 return 0;
 137         }
 138         /* GPIO request and configuration */
 139         ret = devm_gpio_request_one(&client->dev, gpio,
 140                         GPIOF_OUT_INIT_HIGH, "TPM IO LPCPD");
 141         if (ret) {
 142                 dev_err(&client->dev, "Failed to request lpcpd pin\n");
 143                 return -ENODEV;
 144         }
 145         phy->io_lpcpd = gpio;
 146
 147         return 0;
 148 }
 149 #else
 150 static int st33zp24_i2c_of_request_resources(struct st33zp24_i2c_phy *phy)
 151 {
 152         return -ENODEV;
 153 }
 154 #endif
 155
 156 static int st33zp24_i2c_request_resources(struct i2c_client *client,
 157                                           struct st33zp24_i2c_phy *phy)
 158 {
 159         struct st33zp24_platform_data *pdata;
 160         int ret;
 161
 162         pdata = client->dev.platform_data;
 163         if (!pdata) {
 164                 dev_err(&client->dev, "No platform data\n");
 165                 return -ENODEV;
 166         }
 167
 168         /* store for late use */
 169         phy->io_lpcpd = pdata->io_lpcpd;
 170
 171         if (gpio_is_valid(pdata->io_lpcpd)) {
 172                 ret = devm_gpio_request_one(&client->dev,
 173                                 pdata->io_lpcpd, GPIOF_OUT_INIT_HIGH,
 174                                 "TPM IO_LPCPD");
 175                 if (ret) {
 176                         dev_err(&client->dev, "Failed to request lpcpd pin\n");
 177                         return ret;
 178                 }
 179         }
 180
 181         return 0;
 182 }
 183
 184 /*
 185  * st33zp24_i2c_probe initialize the TPM device
 186  * @param: client, the i2c_client drescription (TPM I2C description).
 187  * @param: id, the i2c_device_id struct.
 188  * @return: 0 in case of success.
 189  *       -1 in other case.
 190  */
 191 static int st33zp24_i2c_probe(struct i2c_client *client,
 192                               const struct i2c_device_id *id)
 193 {
 194         int ret;
 195         struct st33zp24_platform_data *pdata;
 196         struct st33zp24_i2c_phy *phy;
 197
 198         if (!client) {
 199                 pr_info("%s: i2c client is NULL. Device not accessible.\n",
 200                         __func__);
 201                 return -ENODEV;
 202         }
 203
 204         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
 205                 dev_info(&client->dev, "client not i2c capable\n");
 206                 return -ENODEV;
 207         }
 208
 209         phy = devm_kzalloc(&client->dev, sizeof(struct st33zp24_i2c_phy),
 210                            GFP_KERNEL);
 211         if (!phy)
 212                 return -ENOMEM;
 213
 214         phy->client = client;
 215         pdata = client->dev.platform_data;
 216         if (!pdata && client->dev.of_node) {
 217                 ret = st33zp24_i2c_of_request_resources(phy);
 218                 if (ret)
 219                         return ret;
 220         } else if (pdata) {
 221                 ret = st33zp24_i2c_request_resources(client, phy);
 222                 if (ret)
 223                         return ret;
 224         }
 225
 226         return st33zp24_probe(phy, &i2c_phy_ops, &client->dev, client->irq,
 227                               phy->io_lpcpd);
 228 }
 229
 230 /*
 231  * st33zp24_i2c_remove remove the TPM device
 232  * @param: client, the i2c_client description (TPM I2C description).
 233  * @return: 0 in case of success.
 234  */
 235 static int st33zp24_i2c_remove(struct i2c_client *client)
 236 {
 237         struct tpm_chip *chip = i2c_get_clientdata(client);
 238
 239         return st33zp24_remove(chip);
 240 }
 241
 242 static const struct i2c_device_id st33zp24_i2c_id[] = {
 243         {TPM_ST33_I2C, 0},
 244         {}
 245 };
 246 MODULE_DEVICE_TABLE(i2c, st33zp24_i2c_id);
 247
 248 #ifdef CONFIG_OF
 249 static const struct of_device_id of_st33zp24_i2c_match[] = {
 250         { .compatible = "st,st33zp24-i2c", },
 251         {}
 252 };
 253 MODULE_DEVICE_TABLE(of, of_st33zp24_i2c_match);
 254 #endif
 255
 256 static SIMPLE_DEV_PM_OPS(st33zp24_i2c_ops, st33zp24_pm_suspend,
 257                          st33zp24_pm_resume);
 258
 259 static struct i2c_driver st33zp24_i2c_driver = {
 260         .driver = {
 261                 .owner = THIS_MODULE,
 262                 .name = TPM_ST33_I2C,
 263                 .pm = &st33zp24_i2c_ops,
 264                 .of_match_table = of_match_ptr(of_st33zp24_i2c_match),
 265         },
 266         .probe = st33zp24_i2c_probe,
 267         .remove = st33zp24_i2c_remove,
 268         .id_table = st33zp24_i2c_id
 269 };
 270
 271 module_i2c_driver(st33zp24_i2c_driver);
 272
 273 MODULE_AUTHOR("TPM support (TPMsupport@list.st.com)");
 274 MODULE_DESCRIPTION("STM TPM 1.2 I2C ST33 Driver");
 275 MODULE_VERSION("1.3.0");
 276 MODULE_LICENSE("GPL");