sonic-buildimage/platform/broadcom/sonic-platform-modules-ragile/common/modules/rg-i2c-gpio.c

/*
 * Bitbanging I2C bus driver using the GPIO API
 *
 * Copyright (C) 2007 Atmel Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>
#include <linux/platform_data/i2c-gpio.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/gpio/consumer.h>
#include <linux/of.h>

extern int rg_i2c_bit_add_numbered_bus(struct i2c_adapter *adap);

struct i2c_gpio_private_data {
    struct gpio_desc *sda;
    struct gpio_desc *scl;
    struct i2c_adapter adap;
    struct i2c_algo_bit_data bit_data;
    struct i2c_gpio_platform_data pdata;
#ifdef CONFIG_I2C_GPIO_FAULT_INJECTOR
    struct dentry *debug_dir;
#endif
};

/*
 * Toggle SDA by changing the output value of the pin. This is only
 * valid for pins configured as open drain (i.e. setting the value
 * high effectively turns off the output driver.)
 */
static void i2c_gpio_setsda_val(void *data, int state)
{
    struct i2c_gpio_private_data *priv = data;

    gpiod_set_value_cansleep(priv->sda, state);
}

/*
 * Toggle SCL by changing the output value of the pin. This is used
 * for pins that are configured as open drain and for output-only
 * pins. The latter case will break the i2c protocol, but it will
 * often work in practice.
 */
static void i2c_gpio_setscl_val(void *data, int state)
{
    struct i2c_gpio_private_data *priv = data;

    gpiod_set_value_cansleep(priv->scl, state);
}

static int i2c_gpio_getsda(void *data)
{
    struct i2c_gpio_private_data *priv = data;

    return gpiod_get_value_cansleep(priv->sda);
}

static int i2c_gpio_getscl(void *data)
{
    struct i2c_gpio_private_data *priv = data;

    return gpiod_get_value_cansleep(priv->scl);
}

#ifdef CONFIG_I2C_GPIO_FAULT_INJECTOR
static struct dentry *i2c_gpio_debug_dir;

#define setsda(bd, val)	((bd)->setsda((bd)->data, val))
#define setscl(bd, val)	((bd)->setscl((bd)->data, val))
#define getsda(bd)	((bd)->getsda((bd)->data))
#define getscl(bd)	((bd)->getscl((bd)->data))

#define WIRE_ATTRIBUTE(wire) \
    static int fops_##wire##_get(void *data, u64 *val)		\
{								\
    struct i2c_gpio_private_data *priv = data;		\
    \
    i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);	\
    *val = get##wire(&priv->bit_data);			\
    i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);	\
    return 0;						\
}								\
static int fops_##wire##_set(void *data, u64 val)		\
{								\
    struct i2c_gpio_private_data *priv = data;		\
    \
    i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);	\
    set##wire(&priv->bit_data, val);			\
    i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);	\
    return 0;						\
}								\
DEFINE_DEBUGFS_ATTRIBUTE(fops_##wire, fops_##wire##_get, fops_##wire##_set, "%llu\n")

WIRE_ATTRIBUTE(scl);
WIRE_ATTRIBUTE(sda);

static void i2c_gpio_incomplete_transfer(struct i2c_gpio_private_data *priv,
        u32 pattern, u8 pattern_size)
{
    struct i2c_algo_bit_data *bit_data = &priv->bit_data;
    int i;

    i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);

    /* START condition */
    setsda(bit_data, 0);
    udelay(bit_data->udelay);

    /* Send pattern, request ACK, don't send STOP */
    for (i = pattern_size - 1; i >= 0; i--) {
        setscl(bit_data, 0);
        udelay(bit_data->udelay / 2);
        setsda(bit_data, (pattern >> i) & 1);
        udelay((bit_data->udelay + 1) / 2);
        setscl(bit_data, 1);
        udelay(bit_data->udelay);
    }

    i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);
}

static int fops_incomplete_addr_phase_set(void *data, u64 addr)
{
    struct i2c_gpio_private_data *priv = data;
    u32 pattern;

    if (addr > 0x7f)
        return -EINVAL;

    /* ADDR (7 bit) + RD (1 bit) + Client ACK, keep SDA hi (1 bit) */
    pattern = (addr << 2) | 3;

    i2c_gpio_incomplete_transfer(priv, pattern, 9);

    return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(fops_incomplete_addr_phase, NULL, fops_incomplete_addr_phase_set, "%llu\n");

static int fops_incomplete_write_byte_set(void *data, u64 addr)
{
    struct i2c_gpio_private_data *priv = data;
    u32 pattern;

    if (addr > 0x7f)
        return -EINVAL;

    /* ADDR (7 bit) + WR (1 bit) + Client ACK (1 bit) */
    pattern = (addr << 2) | 1;
    /* 0x00 (8 bit) + Client ACK, keep SDA hi (1 bit) */
    pattern = (pattern << 9) | 1;

    i2c_gpio_incomplete_transfer(priv, pattern, 18);

    return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(fops_incomplete_write_byte, NULL, fops_incomplete_write_byte_set, "%llu\n");

static void i2c_gpio_fault_injector_init(struct platform_device *pdev)
{
    struct i2c_gpio_private_data *priv = platform_get_drvdata(pdev);

    /*
     * If there will be a debugfs-dir per i2c adapter somewhen, put the
     * 'fault-injector' dir there. Until then, we have a global dir with
     * all adapters as subdirs.
     */
    if (!i2c_gpio_debug_dir) {
        i2c_gpio_debug_dir = debugfs_create_dir("i2c-fault-injector", NULL);
        if (!i2c_gpio_debug_dir)
            return;
    }

    priv->debug_dir = debugfs_create_dir(pdev->name, i2c_gpio_debug_dir);
    if (!priv->debug_dir)
        return;

    debugfs_create_file_unsafe("scl", 0600, priv->debug_dir, priv, &fops_scl);
    debugfs_create_file_unsafe("sda", 0600, priv->debug_dir, priv, &fops_sda);
    debugfs_create_file_unsafe("incomplete_address_phase", 0200, priv->debug_dir,
            priv, &fops_incomplete_addr_phase);
    debugfs_create_file_unsafe("incomplete_write_byte", 0200, priv->debug_dir,
            priv, &fops_incomplete_write_byte);
}

static void i2c_gpio_fault_injector_exit(struct platform_device *pdev)
{
    struct i2c_gpio_private_data *priv = platform_get_drvdata(pdev);

    debugfs_remove_recursive(priv->debug_dir);
}
#else
static inline void i2c_gpio_fault_injector_init(struct platform_device *pdev) {}
static inline void i2c_gpio_fault_injector_exit(struct platform_device *pdev) {}
#endif /* CONFIG_I2C_GPIO_FAULT_INJECTOR*/

static void of_i2c_gpio_get_props(struct device_node *np,
        struct i2c_gpio_platform_data *pdata)
{
    u32 reg;

    of_property_read_u32(np, "i2c-gpio,delay-us", &pdata->udelay);

    if (!of_property_read_u32(np, "i2c-gpio,timeout-ms", &reg))
        pdata->timeout = msecs_to_jiffies(reg);

    pdata->sda_is_open_drain =
        of_property_read_bool(np, "i2c-gpio,sda-open-drain");
    pdata->scl_is_open_drain =
        of_property_read_bool(np, "i2c-gpio,scl-open-drain");
    pdata->scl_is_output_only =
        of_property_read_bool(np, "i2c-gpio,scl-output-only");
}

static struct gpio_desc *i2c_gpio_get_desc(struct device *dev,
        const char *con_id,
        unsigned int index,
        enum gpiod_flags gflags)
{
    struct gpio_desc *retdesc;
    int ret;

    retdesc = devm_gpiod_get(dev, con_id, gflags);
    if (!IS_ERR(retdesc)) {
        dev_dbg(dev, "got GPIO from name %s\n", con_id);
        return retdesc;
    }

    retdesc = devm_gpiod_get_index(dev, NULL, index, gflags);
    if (!IS_ERR(retdesc)) {
        dev_dbg(dev, "got GPIO from index %u\n", index);
        return retdesc;
    }

    ret = PTR_ERR(retdesc);

    /* FIXME: hack in the old code, is this really necessary? */
    if (ret == -EINVAL)
        retdesc = ERR_PTR(-EPROBE_DEFER);

    /* This happens if the GPIO driver is not yet probed, let's defer */
    if (ret == -ENOENT)
        retdesc = ERR_PTR(-EPROBE_DEFER);

    if (PTR_ERR(retdesc) != -EPROBE_DEFER)
        dev_err(dev, "error trying to get descriptor: %d\n", ret);

    return retdesc;
}

static int i2c_gpio_probe(struct platform_device *pdev)
{
    struct i2c_gpio_private_data *priv;
    struct i2c_gpio_platform_data *pdata;
    struct i2c_algo_bit_data *bit_data;
    struct i2c_adapter *adap;
    struct device *dev = &pdev->dev;
    struct device_node *np = dev->of_node;
    enum gpiod_flags gflags;
    int ret;

    priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
    if (!priv)
        return -ENOMEM;

    adap = &priv->adap;
    bit_data = &priv->bit_data;
    pdata = &priv->pdata;

    if (np) {
        of_i2c_gpio_get_props(np, pdata);
    } else {
        /*
         * If all platform data settings are zero it is OK
         * to not provide any platform data from the board.
         */
        if (dev_get_platdata(dev))
            memcpy(pdata, dev_get_platdata(dev), sizeof(*pdata));
    }

    /*
     * First get the GPIO pins; if it fails, we'll defer the probe.
     * If the SDA line is marked from platform data or device tree as
     * "open drain" it means something outside of our control is making
     * this line being handled as open drain, and we should just handle
     * it as any other output. Else we enforce open drain as this is
     * required for an I2C bus.
     */
    if (pdata->sda_is_open_drain)
        gflags = GPIOD_OUT_HIGH;
    else
        gflags = GPIOD_OUT_HIGH_OPEN_DRAIN;
    priv->sda = i2c_gpio_get_desc(dev, "sda", 0, gflags);
    if (IS_ERR(priv->sda))
        return PTR_ERR(priv->sda);

    /*
     * If the SCL line is marked from platform data or device tree as
     * "open drain" it means something outside of our control is making
     * this line being handled as open drain, and we should just handle
     * it as any other output. Else we enforce open drain as this is
     * required for an I2C bus.
     */
    if (pdata->scl_is_open_drain)
        gflags = GPIOD_OUT_HIGH;
    else
        gflags = GPIOD_OUT_HIGH_OPEN_DRAIN;
    priv->scl = i2c_gpio_get_desc(dev, "scl", 1, gflags);
    if (IS_ERR(priv->scl))
        return PTR_ERR(priv->scl);

    if (gpiod_cansleep(priv->sda) || gpiod_cansleep(priv->scl))
        dev_warn(dev, "Slow GPIO pins might wreak havoc into I2C/SMBus bus timing");

    bit_data->setsda = i2c_gpio_setsda_val;
    bit_data->setscl = i2c_gpio_setscl_val;

    if (!pdata->scl_is_output_only)
        bit_data->getscl = i2c_gpio_getscl;
    bit_data->getsda = i2c_gpio_getsda;

    if (pdata->udelay)
        bit_data->udelay = pdata->udelay;
    else if (pdata->scl_is_output_only)
        bit_data->udelay = 50;			/* 10 kHz */
    else
        bit_data->udelay = 5;			/* 100 kHz */

    if (pdata->timeout)
        bit_data->timeout = pdata->timeout;
    else
        bit_data->timeout = HZ / 10;		/* 100 ms */

    bit_data->data = priv;

    adap->owner = THIS_MODULE;
    if (np)
        strlcpy(adap->name, dev_name(dev), sizeof(adap->name));
    else
        snprintf(adap->name, sizeof(adap->name), "i2c-gpio%d", pdev->id);

    adap->algo_data = bit_data;
    adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
    adap->dev.parent = dev;
    adap->dev.of_node = np;

    adap->nr = pdev->id;
    ret = rg_i2c_bit_add_numbered_bus(adap);
    if (ret)
        return ret;

    platform_set_drvdata(pdev, priv);

    /*
     * FIXME: using global GPIO numbers is not helpful. If/when we
     * get accessors to get the actual name of the GPIO line,
     * from the descriptor, then provide that instead.
     */
    dev_info(dev, "using lines %u (SDA) and %u (SCL%s)\n",
            desc_to_gpio(priv->sda), desc_to_gpio(priv->scl),
            pdata->scl_is_output_only
            ? ", no clock stretching" : "");

    i2c_gpio_fault_injector_init(pdev);

    return 0;
}

static int i2c_gpio_remove(struct platform_device *pdev)
{
    struct i2c_gpio_private_data *priv;
    struct i2c_adapter *adap;

    i2c_gpio_fault_injector_exit(pdev);

    priv = platform_get_drvdata(pdev);
    adap = &priv->adap;

    i2c_del_adapter(adap);

    return 0;
}

#if defined(CONFIG_OF)
static const struct of_device_id i2c_gpio_dt_ids[] = {
    { .compatible = "rg-i2c-gpio", },
    { /* sentinel */ }
};

MODULE_DEVICE_TABLE(of, i2c_gpio_dt_ids);
#endif

static struct platform_driver i2c_gpio_driver = {
    .driver		= {
        .name	= "rg-i2c-gpio",
        .of_match_table	= of_match_ptr(i2c_gpio_dt_ids),
    },
    .probe		= i2c_gpio_probe,
    .remove		= i2c_gpio_remove,
};

static int __init i2c_gpio_init(void)
{
    int ret;

    ret = platform_driver_register(&i2c_gpio_driver);
    if (ret)
        printk(KERN_ERR "i2c-gpio: probe failed: %d\n", ret);

    return ret;
}
subsys_initcall(i2c_gpio_init);

static void __exit i2c_gpio_exit(void)
{
    platform_driver_unregister(&i2c_gpio_driver);
}
module_exit(i2c_gpio_exit);

MODULE_AUTHOR("Haavard Skinnemoen (Atmel)");
MODULE_DESCRIPTION("Platform-independent bitbanging I2C driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:i2c-gpio");