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 #define TPM_WRITE_DIRECTION             0x80
  31 #define TPM_BUFSIZE                     2048
  32
  33 struct st33zp24_i2c_phy {
  34         struct i2c_client *client;
  35         u8 buf[TPM_BUFSIZE + 1];
  36         int io_lpcpd;
  37 };
  38
  39 /*
  40  * write8_reg
  41  * Send byte to the TIS register according to the ST33ZP24 I2C protocol.
  42  * @param: tpm_register, the tpm tis register where the data should be written
  43  * @param: tpm_data, the tpm_data to write inside the tpm_register
  44  * @param: tpm_size, The length of the data
  45  * @return: Returns negative errno, or else the number of bytes written.
  46  */
  47 static int write8_reg(void *phy_id, u8 tpm_register, u8 *tpm_data, int tpm_size)
  48 {
  49         struct st33zp24_i2c_phy *phy = phy_id;
  50
  51         phy->buf[0] = tpm_register;
  52         memcpy(phy->buf + 1, tpm_data, tpm_size);
  53         return i2c_master_send(phy->client, phy->buf, tpm_size + 1);
  54 } /* write8_reg() */
  55
  56 /*
  57  * read8_reg
  58  * Recv byte from the TIS register according to the ST33ZP24 I2C protocol.
  59  * @param: tpm_register, the tpm tis register where the data should be read
  60  * @param: tpm_data, the TPM response
  61  * @param: tpm_size, tpm TPM response size to read.
  62  * @return: number of byte read successfully: should be one if success.
  63  */
  64 static int read8_reg(void *phy_id, u8 tpm_register, u8 *tpm_data, int tpm_size)
  65 {
  66         struct st33zp24_i2c_phy *phy = phy_id;
  67         u8 status = 0;
  68         u8 data;
  69
  70         data = TPM_DUMMY_BYTE;
  71         status = write8_reg(phy, tpm_register, &data, 1);
  72         if (status == 2)
  73                 status = i2c_master_recv(phy->client, tpm_data, tpm_size);
  74         return status;
  75 } /* read8_reg() */
  76
  77 /*
  78  * st33zp24_i2c_send
  79  * Send byte to the TIS register according to the ST33ZP24 I2C protocol.
  80  * @param: phy_id, the phy description
  81  * @param: tpm_register, the tpm tis register where the data should be written
  82  * @param: tpm_data, the tpm_data to write inside the tpm_register
  83  * @param: tpm_size, the length of the data
  84  * @return: number of byte written successfully: should be one if success.
  85  */
  86 static int st33zp24_i2c_send(void *phy_id, u8 tpm_register, u8 *tpm_data,
  87                              int tpm_size)
  88 {
  89         return write8_reg(phy_id, tpm_register | TPM_WRITE_DIRECTION, tpm_data,
  90                           tpm_size);
  91 }
  92
  93 /*
  94  * st33zp24_i2c_recv
  95  * Recv byte from the TIS register according to the ST33ZP24 I2C protocol.
  96  * @param: phy_id, the phy description
  97  * @param: tpm_register, the tpm tis register where the data should be read
  98  * @param: tpm_data, the TPM response
  99  * @param: tpm_size, tpm TPM response size to read.
 100  * @return: number of byte read successfully: should be one if success.
 101  */
 102 static int st33zp24_i2c_recv(void *phy_id, u8 tpm_register, u8 *tpm_data,
 103                              int tpm_size)
 104 {
 105         return read8_reg(phy_id, tpm_register, tpm_data, tpm_size);
 106 }
 107
 108 static const struct st33zp24_phy_ops i2c_phy_ops = {
 109         .send = st33zp24_i2c_send,
 110         .recv = st33zp24_i2c_recv,
 111 };
 112
 113 #ifdef CONFIG_OF
 114 static int st33zp24_i2c_of_request_resources(struct st33zp24_i2c_phy *phy)
 115 {
 116         struct device_node *pp;
 117         struct i2c_client *client = phy->client;
 118         int gpio;
 119         int ret;
 120
 121         pp = client->dev.of_node;
 122         if (!pp) {
 123                 dev_err(&client->dev, "No platform data\n");
 124                 return -ENODEV;
 125         }
 126
 127         /* Get GPIO from device tree */
 128         gpio = of_get_named_gpio(pp, "lpcpd-gpios", 0);
 129         if (gpio < 0) {
 130                 dev_err(&client->dev,
 131                         "Failed to retrieve lpcpd-gpios from dts.\n");
 132                 phy->io_lpcpd = -1;
 133                 /*
 134                  * lpcpd pin is not specified. This is not an issue as
 135                  * power management can be also managed by TPM specific
 136                  * commands. So leave with a success status code.
 137                  */
 138                 return 0;
 139         }
 140         /* GPIO request and configuration */
 141         ret = devm_gpio_request_one(&client->dev, gpio,
 142                         GPIOF_OUT_INIT_HIGH, "TPM IO LPCPD");
 143         if (ret) {
 144                 dev_err(&client->dev, "Failed to request lpcpd pin\n");
 145                 return -ENODEV;
 146         }
 147         phy->io_lpcpd = gpio;
 148
 149         return 0;
 150 }
 151 #else
 152 static int st33zp24_i2c_of_request_resources(struct st33zp24_i2c_phy *phy)
 153 {
 154         return -ENODEV;
 155 }
 156 #endif
 157
 158 static int st33zp24_i2c_request_resources(struct i2c_client *client,
 159                                           struct st33zp24_i2c_phy *phy)
 160 {
 161         struct st33zp24_platform_data *pdata;
 162         int ret;
 163
 164         pdata = client->dev.platform_data;
 165         if (!pdata) {
 166                 dev_err(&client->dev, "No platform data\n");
 167                 return -ENODEV;
 168         }
 169
 170         /* store for late use */
 171         phy->io_lpcpd = pdata->io_lpcpd;
 172
 173         if (gpio_is_valid(pdata->io_lpcpd)) {
 174                 ret = devm_gpio_request_one(&client->dev,
 175                                 pdata->io_lpcpd, GPIOF_OUT_INIT_HIGH,
 176                                 "TPM IO_LPCPD");
 177                 if (ret) {
 178                         dev_err(&client->dev, "Failed to request lpcpd pin\n");
 179                         return ret;
 180                 }
 181         }
 182
 183         return 0;
 184 }
 185
 186 /*
 187  * st33zp24_i2c_probe initialize the TPM device
 188  * @param: client, the i2c_client drescription (TPM I2C description).
 189  * @param: id, the i2c_device_id struct.
 190  * @return: 0 in case of success.
 191  *       -1 in other case.
 192  */
 193 static int st33zp24_i2c_probe(struct i2c_client *client,
 194                               const struct i2c_device_id *id)
 195 {
 196         int ret;
 197         struct st33zp24_platform_data *pdata;
 198         struct st33zp24_i2c_phy *phy;
 199
 200         if (!client) {
 201                 pr_info("%s: i2c client is NULL. Device not accessible.\n",
 202                         __func__);
 203                 return -ENODEV;
 204         }
 205
 206         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
 207                 dev_info(&client->dev, "client not i2c capable\n");
 208                 return -ENODEV;
 209         }
 210
 211         phy = devm_kzalloc(&client->dev, sizeof(struct st33zp24_i2c_phy),
 212                            GFP_KERNEL);
 213         if (!phy)
 214                 return -ENOMEM;
 215
 216         phy->client = client;
 217         pdata = client->dev.platform_data;
 218         if (!pdata && client->dev.of_node) {
 219                 ret = st33zp24_i2c_of_request_resources(phy);
 220                 if (ret)
 221                         return ret;
 222         } else if (pdata) {
 223                 ret = st33zp24_i2c_request_resources(client, phy);
 224                 if (ret)
 225                         return ret;
 226         }
 227
 228         return st33zp24_probe(phy, &i2c_phy_ops, &client->dev, client->irq,
 229                               phy->io_lpcpd);
 230 }
 231
 232 /*
 233  * st33zp24_i2c_remove remove the TPM device
 234  * @param: client, the i2c_client description (TPM I2C description).
 235  * @return: 0 in case of success.
 236  */
 237 static int st33zp24_i2c_remove(struct i2c_client *client)
 238 {
 239         struct tpm_chip *chip = i2c_get_clientdata(client);
 240
 241         return st33zp24_remove(chip);
 242 }
 243
 244 static const struct i2c_device_id st33zp24_i2c_id[] = {
 245         {TPM_ST33_I2C, 0},
 246         {}
 247 };
 248 MODULE_DEVICE_TABLE(i2c, st33zp24_i2c_id);
 249
 250 #ifdef CONFIG_OF
 251 static const struct of_device_id of_st33zp24_i2c_match[] = {
 252         { .compatible = "st,st33zp24-i2c", },
 253         {}
 254 };
 255 MODULE_DEVICE_TABLE(of, of_st33zp24_i2c_match);
 256 #endif
 257
 258 static SIMPLE_DEV_PM_OPS(st33zp24_i2c_ops, st33zp24_pm_suspend,
 259                          st33zp24_pm_resume);
 260
 261 static struct i2c_driver st33zp24_i2c_driver = {
 262         .driver = {
 263                 .owner = THIS_MODULE,
 264                 .name = TPM_ST33_I2C,
 265                 .pm = &st33zp24_i2c_ops,
 266                 .of_match_table = of_match_ptr(of_st33zp24_i2c_match),
 267         },
 268         .probe = st33zp24_i2c_probe,
 269         .remove = st33zp24_i2c_remove,
 270         .id_table = st33zp24_i2c_id
 271 };
 272
 273 module_i2c_driver(st33zp24_i2c_driver);
 274
 275 MODULE_AUTHOR("TPM support (TPMsupport@list.st.com)");
 276 MODULE_DESCRIPTION("STM TPM 1.2 I2C ST33 Driver");
 277 MODULE_VERSION("1.3.0");
 278 MODULE_LICENSE("GPL");