drivers/char/tpm/st33zp24/i2c.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * STMicroelectronics TPM I2C Linux driver for TPM ST33ZP24
   4  * Copyright (C) 2009 - 2016 STMicroelectronics
   5  */
   6
   7 #include <linux/module.h>
   8 #include <linux/i2c.h>
   9 #include <linux/of.h>
  10 #include <linux/acpi.h>
  11 #include <linux/tpm.h>
  12
  13 #include "../tpm.h"
  14 #include "st33zp24.h"
  15
  16 #define TPM_DUMMY_BYTE                  0xAA
  17
  18 struct st33zp24_i2c_phy {
  19         struct i2c_client *client;
  20         u8 buf[ST33ZP24_BUFSIZE + 1];
  21 };
  22
  23 /*
  24  * write8_reg
  25  * Send byte to the TIS register according to the ST33ZP24 I2C protocol.
  26  * @param: tpm_register, the tpm tis register where the data should be written
  27  * @param: tpm_data, the tpm_data to write inside the tpm_register
  28  * @param: tpm_size, The length of the data
  29  * @return: Returns negative errno, or else the number of bytes written.
  30  */
  31 static int write8_reg(void *phy_id, u8 tpm_register, u8 *tpm_data, int tpm_size)
  32 {
  33         struct st33zp24_i2c_phy *phy = phy_id;
  34
  35         phy->buf[0] = tpm_register;
  36         memcpy(phy->buf + 1, tpm_data, tpm_size);
  37         return i2c_master_send(phy->client, phy->buf, tpm_size + 1);
  38 } /* write8_reg() */
  39
  40 /*
  41  * read8_reg
  42  * Recv byte from the TIS register according to the ST33ZP24 I2C protocol.
  43  * @param: tpm_register, the tpm tis register where the data should be read
  44  * @param: tpm_data, the TPM response
  45  * @param: tpm_size, tpm TPM response size to read.
  46  * @return: number of byte read successfully: should be one if success.
  47  */
  48 static int read8_reg(void *phy_id, u8 tpm_register, u8 *tpm_data, int tpm_size)
  49 {
  50         struct st33zp24_i2c_phy *phy = phy_id;
  51         u8 status = 0;
  52         u8 data;
  53
  54         data = TPM_DUMMY_BYTE;
  55         status = write8_reg(phy, tpm_register, &data, 1);
  56         if (status == 2)
  57                 status = i2c_master_recv(phy->client, tpm_data, tpm_size);
  58         return status;
  59 } /* read8_reg() */
  60
  61 /*
  62  * st33zp24_i2c_send
  63  * Send byte to the TIS register according to the ST33ZP24 I2C protocol.
  64  * @param: phy_id, the phy description
  65  * @param: tpm_register, the tpm tis register where the data should be written
  66  * @param: tpm_data, the tpm_data to write inside the tpm_register
  67  * @param: tpm_size, the length of the data
  68  * @return: number of byte written successfully: should be one if success.
  69  */
  70 static int st33zp24_i2c_send(void *phy_id, u8 tpm_register, u8 *tpm_data,
  71                              int tpm_size)
  72 {
  73         return write8_reg(phy_id, tpm_register | TPM_WRITE_DIRECTION, tpm_data,
  74                           tpm_size);
  75 }
  76
  77 /*
  78  * st33zp24_i2c_recv
  79  * Recv byte from 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 read
  82  * @param: tpm_data, the TPM response
  83  * @param: tpm_size, tpm TPM response size to read.
  84  * @return: number of byte read successfully: should be one if success.
  85  */
  86 static int st33zp24_i2c_recv(void *phy_id, u8 tpm_register, u8 *tpm_data,
  87                              int tpm_size)
  88 {
  89         return read8_reg(phy_id, tpm_register, tpm_data, tpm_size);
  90 }
  91
  92 static const struct st33zp24_phy_ops i2c_phy_ops = {
  93         .send = st33zp24_i2c_send,
  94         .recv = st33zp24_i2c_recv,
  95 };
  96
  97 /*
  98  * st33zp24_i2c_probe initialize the TPM device
  99  * @param: client, the i2c_client description (TPM I2C description).
 100  * @param: id, the i2c_device_id struct.
 101  * @return: 0 in case of success.
 102  *       -1 in other case.
 103  */
 104 static int st33zp24_i2c_probe(struct i2c_client *client,
 105                               const struct i2c_device_id *id)
 106 {
 107         struct st33zp24_i2c_phy *phy;
 108
 109         if (!client) {
 110                 pr_info("%s: i2c client is NULL. Device not accessible.\n",
 111                         __func__);
 112                 return -ENODEV;
 113         }
 114
 115         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
 116                 dev_info(&client->dev, "client not i2c capable\n");
 117                 return -ENODEV;
 118         }
 119
 120         phy = devm_kzalloc(&client->dev, sizeof(struct st33zp24_i2c_phy),
 121                            GFP_KERNEL);
 122         if (!phy)
 123                 return -ENOMEM;
 124
 125         phy->client = client;
 126
 127         return st33zp24_probe(phy, &i2c_phy_ops, &client->dev, client->irq);
 128 }
 129
 130 /*
 131  * st33zp24_i2c_remove remove the TPM device
 132  * @param: client, the i2c_client description (TPM I2C description).
 133  * @return: 0 in case of success.
 134  */
 135 static void st33zp24_i2c_remove(struct i2c_client *client)
 136 {
 137         struct tpm_chip *chip = i2c_get_clientdata(client);
 138
 139         st33zp24_remove(chip);
 140 }
 141
 142 static const struct i2c_device_id st33zp24_i2c_id[] = {
 143         {TPM_ST33_I2C, 0},
 144         {}
 145 };
 146 MODULE_DEVICE_TABLE(i2c, st33zp24_i2c_id);
 147
 148 static const struct of_device_id of_st33zp24_i2c_match[] = {
 149         { .compatible = "st,st33zp24-i2c", },
 150         {}
 151 };
 152 MODULE_DEVICE_TABLE(of, of_st33zp24_i2c_match);
 153
 154 static const struct acpi_device_id st33zp24_i2c_acpi_match[] = {
 155         {"SMO3324"},
 156         {}
 157 };
 158 MODULE_DEVICE_TABLE(acpi, st33zp24_i2c_acpi_match);
 159
 160 static SIMPLE_DEV_PM_OPS(st33zp24_i2c_ops, st33zp24_pm_suspend,
 161                          st33zp24_pm_resume);
 162
 163 static struct i2c_driver st33zp24_i2c_driver = {
 164         .driver = {
 165                 .name = TPM_ST33_I2C,
 166                 .pm = &st33zp24_i2c_ops,
 167                 .of_match_table = of_match_ptr(of_st33zp24_i2c_match),
 168                 .acpi_match_table = ACPI_PTR(st33zp24_i2c_acpi_match),
 169         },
 170         .probe = st33zp24_i2c_probe,
 171         .remove = st33zp24_i2c_remove,
 172         .id_table = st33zp24_i2c_id
 173 };
 174
 175 module_i2c_driver(st33zp24_i2c_driver);
 176
 177 MODULE_AUTHOR("TPM support (TPMsupport@list.st.com)");
 178 MODULE_DESCRIPTION("STM TPM 1.2 I2C ST33 Driver");
 179 MODULE_VERSION("1.3.0");
 180 MODULE_LICENSE("GPL");