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linux/drivers/i2c/busses/i2c-emev2.c

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/*
* I2C driver for the Renesas EMEV2 SoC
*
* Copyright (C) 2015 Wolfram Sang <wsa@sang-engineering.com>
* Copyright 2013 Codethink Ltd.
* Copyright 2010-2015 Renesas Electronics 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/clk.h>
#include <linux/completion.h>
#include <linux/device.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/sched.h>
/* I2C Registers */
#define I2C_OFS_IICACT0 0x00 /* start */
#define I2C_OFS_IIC0 0x04 /* shift */
#define I2C_OFS_IICC0 0x08 /* control */
#define I2C_OFS_SVA0 0x0c /* slave address */
#define I2C_OFS_IICCL0 0x10 /* clock select */
#define I2C_OFS_IICX0 0x14 /* extension */
#define I2C_OFS_IICS0 0x18 /* status */
#define I2C_OFS_IICSE0 0x1c /* status For emulation */
#define I2C_OFS_IICF0 0x20 /* IIC flag */
/* I2C IICACT0 Masks */
#define I2C_BIT_IICE0 0x0001
/* I2C IICC0 Masks */
#define I2C_BIT_LREL0 0x0040
#define I2C_BIT_WREL0 0x0020
#define I2C_BIT_SPIE0 0x0010
#define I2C_BIT_WTIM0 0x0008
#define I2C_BIT_ACKE0 0x0004
#define I2C_BIT_STT0 0x0002
#define I2C_BIT_SPT0 0x0001
/* I2C IICCL0 Masks */
#define I2C_BIT_SMC0 0x0008
#define I2C_BIT_DFC0 0x0004
/* I2C IICSE0 Masks */
#define I2C_BIT_MSTS0 0x0080
#define I2C_BIT_ALD0 0x0040
#define I2C_BIT_EXC0 0x0020
#define I2C_BIT_COI0 0x0010
#define I2C_BIT_TRC0 0x0008
#define I2C_BIT_ACKD0 0x0004
#define I2C_BIT_STD0 0x0002
#define I2C_BIT_SPD0 0x0001
/* I2C IICF0 Masks */
#define I2C_BIT_STCF 0x0080
#define I2C_BIT_IICBSY 0x0040
#define I2C_BIT_STCEN 0x0002
#define I2C_BIT_IICRSV 0x0001
struct em_i2c_device {
void __iomem *base;
struct i2c_adapter adap;
struct completion msg_done;
struct clk *sclk;
};
static inline void em_clear_set_bit(struct em_i2c_device *priv, u8 clear, u8 set, u8 reg)
{
writeb((readb(priv->base + reg) & ~clear) | set, priv->base + reg);
}
static int em_i2c_wait_for_event(struct em_i2c_device *priv)
{
unsigned long time_left;
int status;
reinit_completion(&priv->msg_done);
time_left = wait_for_completion_timeout(&priv->msg_done, priv->adap.timeout);
if (!time_left)
return -ETIMEDOUT;
status = readb(priv->base + I2C_OFS_IICSE0);
return status & I2C_BIT_ALD0 ? -EAGAIN : status;
}
static void em_i2c_stop(struct em_i2c_device *priv)
{
/* Send Stop condition */
em_clear_set_bit(priv, 0, I2C_BIT_SPT0 | I2C_BIT_SPIE0, I2C_OFS_IICC0);
/* Wait for stop condition */
em_i2c_wait_for_event(priv);
}
static void em_i2c_reset(struct i2c_adapter *adap)
{
struct em_i2c_device *priv = i2c_get_adapdata(adap);
int retr;
/* If I2C active */
if (readb(priv->base + I2C_OFS_IICACT0) & I2C_BIT_IICE0) {
/* Disable I2C operation */
writeb(0, priv->base + I2C_OFS_IICACT0);
retr = 1000;
while (readb(priv->base + I2C_OFS_IICACT0) == 1 && retr)
retr--;
WARN_ON(retr == 0);
}
/* Transfer mode set */
writeb(I2C_BIT_DFC0, priv->base + I2C_OFS_IICCL0);
/* Can Issue start without detecting a stop, Reservation disabled. */
writeb(I2C_BIT_STCEN | I2C_BIT_IICRSV, priv->base + I2C_OFS_IICF0);
/* I2C enable, 9 bit interrupt mode */
writeb(I2C_BIT_WTIM0, priv->base + I2C_OFS_IICC0);
/* Enable I2C operation */
writeb(I2C_BIT_IICE0, priv->base + I2C_OFS_IICACT0);
retr = 1000;
while (readb(priv->base + I2C_OFS_IICACT0) == 0 && retr)
retr--;
WARN_ON(retr == 0);
}
static int __em_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msg,
int stop)
{
struct em_i2c_device *priv = i2c_get_adapdata(adap);
int count, status, read = !!(msg->flags & I2C_M_RD);
/* Send start condition */
em_clear_set_bit(priv, 0, I2C_BIT_ACKE0 | I2C_BIT_WTIM0, I2C_OFS_IICC0);
em_clear_set_bit(priv, 0, I2C_BIT_STT0, I2C_OFS_IICC0);
/* Send slave address and R/W type */
writeb((msg->addr << 1) | read, priv->base + I2C_OFS_IIC0);
/* Wait for transaction */
status = em_i2c_wait_for_event(priv);
if (status < 0)
goto out_reset;
/* Received NACK (result of setting slave address and R/W) */
if (!(status & I2C_BIT_ACKD0)) {
em_i2c_stop(priv);
goto out;
}
/* Extra setup for read transactions */
if (read) {
/* 8 bit interrupt mode */
em_clear_set_bit(priv, I2C_BIT_WTIM0, I2C_BIT_ACKE0, I2C_OFS_IICC0);
em_clear_set_bit(priv, I2C_BIT_WTIM0, I2C_BIT_WREL0, I2C_OFS_IICC0);
/* Wait for transaction */
status = em_i2c_wait_for_event(priv);
if (status < 0)
goto out_reset;
}
/* Send / receive data */
for (count = 0; count < msg->len; count++) {
if (read) { /* Read transaction */
msg->buf[count] = readb(priv->base + I2C_OFS_IIC0);
em_clear_set_bit(priv, 0, I2C_BIT_WREL0, I2C_OFS_IICC0);
} else { /* Write transaction */
/* Received NACK */
if (!(status & I2C_BIT_ACKD0)) {
em_i2c_stop(priv);
goto out;
}
/* Write data */
writeb(msg->buf[count], priv->base + I2C_OFS_IIC0);
}
/* Wait for R/W transaction */
status = em_i2c_wait_for_event(priv);
if (status < 0)
goto out_reset;
}
if (stop)
em_i2c_stop(priv);
return count;
out_reset:
em_i2c_reset(adap);
out:
return status < 0 ? status : -ENXIO;
}
static int em_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
int num)
{
struct em_i2c_device *priv = i2c_get_adapdata(adap);
int ret, i;
if (readb(priv->base + I2C_OFS_IICF0) & I2C_BIT_IICBSY)
return -EAGAIN;
for (i = 0; i < num; i++) {
ret = __em_i2c_xfer(adap, &msgs[i], (i == (num - 1)));
if (ret < 0)
return ret;
}
/* I2C transfer completed */
return num;
}
static irqreturn_t em_i2c_irq_handler(int this_irq, void *dev_id)
{
struct em_i2c_device *priv = dev_id;
complete(&priv->msg_done);
return IRQ_HANDLED;
}
static u32 em_i2c_func(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}
static struct i2c_algorithm em_i2c_algo = {
.master_xfer = em_i2c_xfer,
.functionality = em_i2c_func,
};
static int em_i2c_probe(struct platform_device *pdev)
{
struct em_i2c_device *priv;
struct resource *r;
int irq, ret;
priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
priv->base = devm_ioremap_resource(&pdev->dev, r);
if (IS_ERR(priv->base))
return PTR_ERR(priv->base);
strlcpy(priv->adap.name, "EMEV2 I2C", sizeof(priv->adap.name));
priv->sclk = devm_clk_get(&pdev->dev, "sclk");
if (IS_ERR(priv->sclk))
return PTR_ERR(priv->sclk);
clk_prepare_enable(priv->sclk);
priv->adap.timeout = msecs_to_jiffies(100);
priv->adap.retries = 5;
priv->adap.dev.parent = &pdev->dev;
priv->adap.algo = &em_i2c_algo;
priv->adap.owner = THIS_MODULE;
priv->adap.dev.of_node = pdev->dev.of_node;
init_completion(&priv->msg_done);
platform_set_drvdata(pdev, priv);
i2c_set_adapdata(&priv->adap, priv);
em_i2c_reset(&priv->adap);
irq = platform_get_irq(pdev, 0);
ret = devm_request_irq(&pdev->dev, irq, em_i2c_irq_handler, 0,
"em_i2c", priv);
if (ret)
goto err_clk;
ret = i2c_add_adapter(&priv->adap);
if (ret)
goto err_clk;
dev_info(&pdev->dev, "Added i2c controller %d, irq %d\n", priv->adap.nr, irq);
return 0;
err_clk:
clk_disable_unprepare(priv->sclk);
return ret;
}
static int em_i2c_remove(struct platform_device *dev)
{
struct em_i2c_device *priv = platform_get_drvdata(dev);
i2c_del_adapter(&priv->adap);
clk_disable_unprepare(priv->sclk);
return 0;
}
static const struct of_device_id em_i2c_ids[] = {
{ .compatible = "renesas,iic-emev2", },
{ }
};
static struct platform_driver em_i2c_driver = {
.probe = em_i2c_probe,
.remove = em_i2c_remove,
.driver = {
.name = "em-i2c",
.of_match_table = em_i2c_ids,
}
};
module_platform_driver(em_i2c_driver);
MODULE_DESCRIPTION("EMEV2 I2C bus driver");
MODULE_AUTHOR("Ian Molton and Wolfram Sang <wsa@sang-engineering.com>");
MODULE_LICENSE("GPL v2");
MODULE_DEVICE_TABLE(of, em_i2c_ids);
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