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// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2014 Panasonic Corporation
* Copyright (C) 2015-2016 Socionext Inc.
* Author: Masahiro Yamada <yamada.masahiro@socionext.com>
*/
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/io.h>
#include <linux/sizes.h>
#include <linux/types.h>
#include <dm.h>
#include <fdtdec.h>
#include <i2c.h>
struct uniphier_i2c_regs {
u32 dtrm; /* data transmission */
#define I2C_DTRM_STA (1 << 10)
#define I2C_DTRM_STO (1 << 9)
#define I2C_DTRM_NACK (1 << 8)
#define I2C_DTRM_RD (1 << 0)
u32 drec; /* data reception */
#define I2C_DREC_STS (1 << 12)
#define I2C_DREC_LRB (1 << 11)
#define I2C_DREC_LAB (1 << 9)
u32 myad; /* slave address */
u32 clk; /* clock frequency control */
u32 brst; /* bus reset */
#define I2C_BRST_FOEN (1 << 1)
#define I2C_BRST_BRST (1 << 0)
u32 hold; /* hold time control */
u32 bsts; /* bus status monitor */
u32 noise; /* noise filter control */
u32 setup; /* setup time control */
};
#define IOBUS_FREQ 100000000
struct uniphier_i2c_priv {
struct udevice *dev;
struct uniphier_i2c_regs __iomem *regs; /* register base */
unsigned long input_clk; /* master clock (Hz) */
unsigned long wait_us; /* wait for every byte transfer (us) */
};
static int uniphier_i2c_probe(struct udevice *dev)
{
fdt_addr_t addr;
struct uniphier_i2c_priv *priv = dev_get_priv(dev);
addr = devfdt_get_addr(dev);
if (addr == FDT_ADDR_T_NONE)
return -EINVAL;
priv->regs = devm_ioremap(dev, addr, SZ_64);
if (!priv->regs)
return -ENOMEM;
priv->input_clk = IOBUS_FREQ;
priv->dev = dev;
/* deassert reset */
writel(0x3, &priv->regs->brst);
return 0;
}
static int send_and_recv_byte(struct uniphier_i2c_priv *priv, u32 dtrm)
{
writel(dtrm, &priv->regs->dtrm);
/*
* This controller only provides interruption to inform the completion
* of each byte transfer. (No status register to poll it.)
* Unfortunately, U-Boot does not have a good support of interrupt.
* Wait for a while.
*/
udelay(priv->wait_us);
return readl(&priv->regs->drec);
}
static int send_byte(struct uniphier_i2c_priv *priv, u32 dtrm, bool *stop)
{
int ret = 0;
u32 drec;
drec = send_and_recv_byte(priv, dtrm);
if (drec & I2C_DREC_LAB) {
dev_dbg(priv->dev, "uniphier_i2c: bus arbitration failed\n");
*stop = false;
ret = -EREMOTEIO;
}
if (drec & I2C_DREC_LRB) {
dev_dbg(priv->dev, "uniphier_i2c: slave did not return ACK\n");
ret = -EREMOTEIO;
}
return ret;
}
static int uniphier_i2c_transmit(struct uniphier_i2c_priv *priv, uint addr,
uint len, const u8 *buf, bool *stop)
{
int ret;
dev_dbg(priv->dev, "%s: addr = %x, len = %d\n", __func__, addr, len);
ret = send_byte(priv, I2C_DTRM_STA | I2C_DTRM_NACK | addr << 1, stop);
if (ret < 0)
goto fail;
while (len--) {
ret = send_byte(priv, I2C_DTRM_NACK | *buf++, stop);
if (ret < 0)
goto fail;
}
fail:
if (*stop)
writel(I2C_DTRM_STO | I2C_DTRM_NACK, &priv->regs->dtrm);
return ret;
}
static int uniphier_i2c_receive(struct uniphier_i2c_priv *priv, uint addr,
uint len, u8 *buf, bool *stop)
{
int ret;
dev_dbg(priv->dev, "%s: addr = %x, len = %d\n", __func__, addr, len);
ret = send_byte(priv, I2C_DTRM_STA | I2C_DTRM_NACK |
I2C_DTRM_RD | addr << 1, stop);
if (ret < 0)
goto fail;
while (len--)
*buf++ = send_and_recv_byte(priv, len ? 0 : I2C_DTRM_NACK);
fail:
if (*stop)
writel(I2C_DTRM_STO | I2C_DTRM_NACK, &priv->regs->dtrm);
return ret;
}
static int uniphier_i2c_xfer(struct udevice *bus, struct i2c_msg *msg,
int nmsgs)
{
int ret = 0;
struct uniphier_i2c_priv *priv = dev_get_priv(bus);
bool stop;
for (; nmsgs > 0; nmsgs--, msg++) {
/* If next message is read, skip the stop condition */
stop = nmsgs > 1 && msg[1].flags & I2C_M_RD ? false : true;
if (msg->flags & I2C_M_RD)
ret = uniphier_i2c_receive(priv, msg->addr, msg->len,
msg->buf, &stop);
else
ret = uniphier_i2c_transmit(priv, msg->addr, msg->len,
msg->buf, &stop);
if (ret < 0)
break;
}
return ret;
}
static int uniphier_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
{
struct uniphier_i2c_priv *priv = dev_get_priv(bus);
/* max supported frequency is 400 kHz */
if (speed > I2C_SPEED_FAST_RATE)
return -EINVAL;
/* bus reset: make sure the bus is idle when change the frequency */
writel(0x1, &priv->regs->brst);
writel((priv->input_clk / speed / 2 << 16) | (priv->input_clk / speed),
&priv->regs->clk);
writel(0x3, &priv->regs->brst);
/*
* Theoretically, each byte can be transferred in
* 1000000 * 9 / speed usec. For safety, wait more than double.
*/
priv->wait_us = 20000000 / speed;
return 0;
}
static const struct dm_i2c_ops uniphier_i2c_ops = {
.xfer = uniphier_i2c_xfer,
.set_bus_speed = uniphier_i2c_set_bus_speed,
};
static const struct udevice_id uniphier_i2c_of_match[] = {
{ .compatible = "socionext,uniphier-i2c" },
{ /* sentinel */ }
};
U_BOOT_DRIVER(uniphier_i2c) = {
.name = "uniphier-i2c",
.id = UCLASS_I2C,
.of_match = uniphier_i2c_of_match,
.probe = uniphier_i2c_probe,
.priv_auto_alloc_size = sizeof(struct uniphier_i2c_priv),
.ops = &uniphier_i2c_ops,
};
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