222 lines
5.2 KiB
C
222 lines
5.2 KiB
C
/*
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* Bitbanging I2C bus driver using the GPIO API
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*
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* Copyright (C) 2007 Atmel Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <common.h>
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#include <driver.h>
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#include <i2c/i2c.h>
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#include <i2c/i2c-algo-bit.h>
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#include <i2c/i2c-gpio.h>
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#include <init.h>
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#include <gpio.h>
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#include <of_gpio.h>
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struct i2c_gpio_private_data {
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struct i2c_adapter adap;
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struct i2c_algo_bit_data bit_data;
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struct i2c_gpio_platform_data pdata;
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};
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/* Toggle SDA by changing the direction of the pin */
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static void i2c_gpio_setsda_dir(void *data, int state)
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{
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struct i2c_gpio_platform_data *pdata = data;
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if (state)
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gpio_direction_input(pdata->sda_pin);
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else
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gpio_direction_output(pdata->sda_pin, 0);
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}
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/*
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* Toggle SDA by changing the output value of the pin. This is only
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* valid for pins configured as open drain (i.e. setting the value
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* high effectively turns off the output driver.)
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*/
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static void i2c_gpio_setsda_val(void *data, int state)
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{
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struct i2c_gpio_platform_data *pdata = data;
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gpio_set_value(pdata->sda_pin, state);
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}
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/* Toggle SCL by changing the direction of the pin. */
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static void i2c_gpio_setscl_dir(void *data, int state)
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{
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struct i2c_gpio_platform_data *pdata = data;
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if (state)
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gpio_direction_input(pdata->scl_pin);
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else
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gpio_direction_output(pdata->scl_pin, 0);
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}
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/*
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* Toggle SCL by changing the output value of the pin. This is used
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* for pins that are configured as open drain and for output-only
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* pins. The latter case will break the i2c protocol, but it will
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* often work in practice.
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*/
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static void i2c_gpio_setscl_val(void *data, int state)
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{
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struct i2c_gpio_platform_data *pdata = data;
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gpio_set_value(pdata->scl_pin, state);
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}
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static int i2c_gpio_getsda(void *data)
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{
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struct i2c_gpio_platform_data *pdata = data;
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return gpio_get_value(pdata->sda_pin);
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}
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static int i2c_gpio_getscl(void *data)
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{
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struct i2c_gpio_platform_data *pdata = data;
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return gpio_get_value(pdata->scl_pin);
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}
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static int of_i2c_gpio_probe(struct device_node *np,
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struct i2c_gpio_platform_data *pdata)
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{
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u32 reg;
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if (!IS_ENABLED(CONFIG_OFDEVICE))
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return -ENODEV;
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if (of_gpio_count(np) < 2)
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return -ENODEV;
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pdata->sda_pin = of_get_gpio(np, 0);
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pdata->scl_pin = of_get_gpio(np, 1);
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if (!gpio_is_valid(pdata->sda_pin) || !gpio_is_valid(pdata->scl_pin)) {
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pr_err("%s: invalid GPIO pins, sda=%d/scl=%d\n",
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np->full_name, pdata->sda_pin, pdata->scl_pin);
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return -ENODEV;
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}
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of_property_read_u32(np, "i2c-gpio,delay-us", &pdata->udelay);
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if (!of_property_read_u32(np, "i2c-gpio,timeout-ms", ®))
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pdata->timeout_ms = reg;
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pdata->sda_is_open_drain =
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of_property_read_bool(np, "i2c-gpio,sda-open-drain");
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pdata->scl_is_open_drain =
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of_property_read_bool(np, "i2c-gpio,scl-open-drain");
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pdata->scl_is_output_only =
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of_property_read_bool(np, "i2c-gpio,scl-output-only");
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return 0;
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}
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static int i2c_gpio_probe(struct device_d *dev)
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{
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struct i2c_gpio_private_data *priv;
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struct i2c_gpio_platform_data *pdata;
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struct i2c_algo_bit_data *bit_data;
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struct i2c_adapter *adap;
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int ret;
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priv = xzalloc(sizeof(*priv));
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adap = &priv->adap;
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bit_data = &priv->bit_data;
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pdata = &priv->pdata;
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if (dev->device_node) {
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ret = of_i2c_gpio_probe(dev->device_node, pdata);
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if (ret)
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return ret;
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} else {
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if (!dev->platform_data)
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return -ENXIO;
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memcpy(pdata, dev->platform_data, sizeof(*pdata));
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}
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ret = gpio_request(pdata->sda_pin, "sda");
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if (ret)
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goto err_request_sda;
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ret = gpio_request(pdata->scl_pin, "scl");
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if (ret)
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goto err_request_scl;
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if (pdata->sda_is_open_drain) {
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gpio_direction_output(pdata->sda_pin, 1);
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bit_data->setsda = i2c_gpio_setsda_val;
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} else {
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gpio_direction_input(pdata->sda_pin);
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bit_data->setsda = i2c_gpio_setsda_dir;
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}
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if (pdata->scl_is_open_drain || pdata->scl_is_output_only) {
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gpio_direction_output(pdata->scl_pin, 1);
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bit_data->setscl = i2c_gpio_setscl_val;
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} else {
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gpio_direction_input(pdata->scl_pin);
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bit_data->setscl = i2c_gpio_setscl_dir;
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}
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if (!pdata->scl_is_output_only)
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bit_data->getscl = i2c_gpio_getscl;
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bit_data->getsda = i2c_gpio_getsda;
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if (pdata->udelay)
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bit_data->udelay = pdata->udelay;
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else if (pdata->scl_is_output_only)
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bit_data->udelay = 50; /* 10 kHz */
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else
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bit_data->udelay = 5; /* 100 kHz */
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if (pdata->timeout_ms)
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bit_data->timeout_ms = pdata->timeout_ms;
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else
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bit_data->timeout_ms = 100; /* 100 ms */
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bit_data->data = pdata;
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adap->algo_data = bit_data;
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adap->dev.parent = dev;
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adap->dev.device_node = dev->device_node;
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adap->nr = dev->id;
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ret = i2c_bit_add_numbered_bus(adap);
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if (ret)
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goto err_add_bus;
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dev_info(dev, "using pins %u (SDA) and %u (SCL%s)\n",
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pdata->sda_pin, pdata->scl_pin,
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pdata->scl_is_output_only
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? ", no clock stretching" : "");
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return 0;
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err_add_bus:
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gpio_free(pdata->scl_pin);
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err_request_scl:
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gpio_free(pdata->sda_pin);
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err_request_sda:
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return ret;
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}
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static struct of_device_id i2c_gpio_dt_ids[] = {
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{ .compatible = "i2c-gpio", },
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{ /* sentinel */ }
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};
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static struct driver_d i2c_gpio_driver = {
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.name = "i2c-gpio",
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.probe = i2c_gpio_probe,
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.of_compatible = DRV_OF_COMPAT(i2c_gpio_dt_ids),
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};
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device_platform_driver(i2c_gpio_driver);
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