diff options
Diffstat (limited to 'drivers/i2c/i2c-core-slave.c')
| -rw-r--r-- | drivers/i2c/i2c-core-slave.c | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/drivers/i2c/i2c-core-slave.c b/drivers/i2c/i2c-core-slave.c new file mode 100644 index 000000000..f2e7e373e --- /dev/null +++ b/drivers/i2c/i2c-core-slave.c @@ -0,0 +1,116 @@ +/* + * Linux I2C core slave support code + * + * Copyright (C) 2014 by Wolfram Sang <wsa@sang-engineering.com> + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the Free + * Software Foundation; either version 2 of the License, or (at your option) + * any later version. + */ + +#include <dt-bindings/i2c/i2c.h> +#include <linux/acpi.h> +#include <linux/device.h> +#include <linux/err.h> +#include <linux/i2c.h> +#include <linux/of.h> + +#include "i2c-core.h" + +int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb) +{ + int ret; + + if (WARN(IS_ERR_OR_NULL(client) || !slave_cb, "insufficient data\n")) + return -EINVAL; + + if (!(client->flags & I2C_CLIENT_SLAVE)) + dev_warn(&client->dev, "%s: client slave flag not set. You might see address collisions\n", + __func__); + + if (!(client->flags & I2C_CLIENT_TEN)) { + /* Enforce stricter address checking */ + ret = i2c_check_7bit_addr_validity_strict(client->addr); + if (ret) { + dev_err(&client->dev, "%s: invalid address\n", __func__); + return ret; + } + } + + if (!client->adapter->algo->reg_slave) { + dev_err(&client->dev, "%s: not supported by adapter\n", __func__); + return -EOPNOTSUPP; + } + + client->slave_cb = slave_cb; + + i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER); + ret = client->adapter->algo->reg_slave(client); + i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER); + + if (ret) { + client->slave_cb = NULL; + dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret); + } + + return ret; +} +EXPORT_SYMBOL_GPL(i2c_slave_register); + +int i2c_slave_unregister(struct i2c_client *client) +{ + int ret; + + if (IS_ERR_OR_NULL(client)) + return -EINVAL; + + if (!client->adapter->algo->unreg_slave) { + dev_err(&client->dev, "%s: not supported by adapter\n", __func__); + return -EOPNOTSUPP; + } + + i2c_lock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER); + ret = client->adapter->algo->unreg_slave(client); + i2c_unlock_bus(client->adapter, I2C_LOCK_ROOT_ADAPTER); + + if (ret == 0) + client->slave_cb = NULL; + else + dev_err(&client->dev, "%s: adapter returned error %d\n", __func__, ret); + + return ret; +} +EXPORT_SYMBOL_GPL(i2c_slave_unregister); + +/** + * i2c_detect_slave_mode - detect operation mode + * @dev: The device owning the bus + * + * This checks the device nodes for an I2C slave by checking the address + * used in the reg property. If the address match the I2C_OWN_SLAVE_ADDRESS + * flag this means the device is configured to act as a I2C slave and it will + * be listening at that address. + * + * Returns true if an I2C own slave address is detected, otherwise returns + * false. + */ +bool i2c_detect_slave_mode(struct device *dev) +{ + if (IS_BUILTIN(CONFIG_OF) && dev->of_node) { + struct device_node *child; + u32 reg; + + for_each_child_of_node(dev->of_node, child) { + of_property_read_u32(child, "reg", ®); + if (reg & I2C_OWN_SLAVE_ADDRESS) { + of_node_put(child); + return true; + } + } + } else if (IS_BUILTIN(CONFIG_ACPI) && ACPI_HANDLE(dev)) { + dev_dbg(dev, "ACPI slave is not supported yet\n"); + } + return false; +} +EXPORT_SYMBOL_GPL(i2c_detect_slave_mode); |