src/include/device/i2c_bus.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2
   3 #ifndef _DEVICE_I2C_BUS_H_
   4 #define _DEVICE_I2C_BUS_H_
   5
   6 #include <stddef.h>
   7 #include <stdint.h>
   8 #include <device/i2c.h>
   9 #include <device/device.h>
  10
  11 /* I2C bus operation for ramstage drivers */
  12 struct i2c_bus_operations {
  13         int (*transfer)(struct device *, const struct i2c_msg *, size_t count);
  14 };
  15
  16 /**
  17  * Determine device presence at a given slave address.
  18  */
  19 bool i2c_dev_detect(struct device *dev, unsigned int addr);
  20
  21 /*
  22  * Returns the first upstream facing link whose bus implements either
  23  * `i2c_bus_operations` *or* `smbus_bus_operations`.
  24  *
  25  * If not NULL, guarantees that `->dev`, `->dev->ops` and either
  26  * `->dev->ops->ops_i2c_bus` or `->dev->ops->ops_smbus_bus` are
  27  * not NULL.
  28  */
  29 struct bus *i2c_link(const struct device *dev);
  30
  31 /*
  32  * Shorthand for `i2c_link(dev)->dev`.
  33  *
  34  * Returns NULL if i2c_link(dev) returns NULL.
  35  */
  36 static inline DEVTREE_CONST struct device *i2c_busdev(const struct device *dev)
  37 {
  38         struct bus *const link = i2c_link(dev);
  39         return link ? link->dev : NULL;
  40 }
  41
  42 /*
  43  * Slave driver interface functions. These will look for the next
  44  * `i2c_bus_operations` *or* `smbus_bus_operations` and perform the
  45  * respective transfers.
  46  *
  47  * The interface is limited to what current slave drivers demand.
  48  * Extend as required.
  49  *
  50  * All functions return a negative `enum cb_err` value on error.
  51  * Either CB_ERR, CB_ERR_ARG or any CB_I2C_* (cf. include/types.h).
  52  */
  53
  54 /*
  55  * Reads one byte.
  56  * Compatible to smbus_recv_byte().
  57  *
  58  * Returns the read byte on success, negative `enum cb_err` value on error.
  59  */
  60 int i2c_dev_readb(struct device *);
  61
  62 /*
  63  * Writes the byte `val`.
  64  * Compatible to smbus_send_byte().
  65  *
  66  * Returns 0 on success, negative `enum cb_err` value on error.
  67  */
  68 int i2c_dev_writeb(struct device *, uint8_t val);
  69
  70 /*
  71  * Sends the register offset `off` and reads one byte.
  72  * Compatible to smbus_read_byte().
  73  *
  74  * Returns the read byte on success, negative `enum cb_err` value on error.
  75  */
  76 int i2c_dev_readb_at(struct device *, uint8_t off);
  77
  78 /*
  79  * Sends the register offset `off` followed by the byte `val`.
  80  * Compatible to smbus_write_byte().
  81  *
  82  * Returns 0 on success, negative `enum cb_err` value on error.
  83  */
  84 int i2c_dev_writeb_at(struct device *, uint8_t off, uint8_t val);
  85
  86 /*
  87  * Sends the 16-bit register offset `off` and reads `len` bytes into `buf`.
  88  *
  89  * Returns the number of bytes read on success, negative `enum cb_err`
  90  * value on error.
  91  */
  92 int i2c_dev_read_at16(struct device *, uint8_t *buf, size_t len, uint16_t off);
  93 /*
  94  * Sends the 8-bit register offset `off` and reads `len` bytes into `buf`.
  95  *
  96  * Returns the number of bytes read on success, negative `enum cb_err`
  97  * value on error.
  98  */
  99 int i2c_dev_read_at(struct device *, uint8_t *buf, size_t len, uint8_t off);
 100 /*
 101  * Sends the 8-bit register offset `off` and writes `len` bytes from `buf`.
 102  *
 103  * Returns the number of bytes written on success, negative `enum cb_err`
 104  * value on error.
 105  */
 106 int i2c_dev_write_at(struct device *, uint8_t *buf, size_t len, uint8_t off);
 107
 108 #endif  /* _DEVICE_I2C_BUS_H_ */