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alistair23-linux/drivers/i2c/busses/i2c-lpc2k.c
Thomas Gleixner 2874c5fd28 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 
Based on 1 normalized pattern(s):

  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

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-30 11:26:32 -07:00

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2011 NXP Semiconductors
*
* Code portions referenced from the i2x-pxa and i2c-pnx drivers
*
* Make SMBus byte and word transactions work on LPC178x/7x
* Copyright (c) 2012
* Alexander Potashev, Emcraft Systems, aspotashev@emcraft.com
* Anton Protopopov, Emcraft Systems, antonp@emcraft.com
*
* Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com>
*/
#include <linux/clk.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/sched.h>
#include <linux/time.h>
/* LPC24xx register offsets and bits */
#define LPC24XX_I2CONSET 0x00
#define LPC24XX_I2STAT 0x04
#define LPC24XX_I2DAT 0x08
#define LPC24XX_I2ADDR 0x0c
#define LPC24XX_I2SCLH 0x10
#define LPC24XX_I2SCLL 0x14
#define LPC24XX_I2CONCLR 0x18
#define LPC24XX_AA BIT(2)
#define LPC24XX_SI BIT(3)
#define LPC24XX_STO BIT(4)
#define LPC24XX_STA BIT(5)
#define LPC24XX_I2EN BIT(6)
#define LPC24XX_STO_AA (LPC24XX_STO | LPC24XX_AA)
#define LPC24XX_CLEAR_ALL (LPC24XX_AA | LPC24XX_SI | LPC24XX_STO | \
LPC24XX_STA | LPC24XX_I2EN)
/* I2C SCL clock has different duty cycle depending on mode */
#define I2C_STD_MODE_DUTY 46
#define I2C_FAST_MODE_DUTY 36
#define I2C_FAST_MODE_PLUS_DUTY 38
/*
* 26 possible I2C status codes, but codes applicable only
* to master are listed here and used in this driver
*/
enum {
M_BUS_ERROR = 0x00,
M_START = 0x08,
M_REPSTART = 0x10,
MX_ADDR_W_ACK = 0x18,
MX_ADDR_W_NACK = 0x20,
MX_DATA_W_ACK = 0x28,
MX_DATA_W_NACK = 0x30,
M_DATA_ARB_LOST = 0x38,
MR_ADDR_R_ACK = 0x40,
MR_ADDR_R_NACK = 0x48,
MR_DATA_R_ACK = 0x50,
MR_DATA_R_NACK = 0x58,
M_I2C_IDLE = 0xf8,
};
struct lpc2k_i2c {
void __iomem *base;
struct clk *clk;
int irq;
wait_queue_head_t wait;
struct i2c_adapter adap;
struct i2c_msg *msg;
int msg_idx;
int msg_status;
int is_last;
};
static void i2c_lpc2k_reset(struct lpc2k_i2c *i2c)
{
/* Will force clear all statuses */
writel(LPC24XX_CLEAR_ALL, i2c->base + LPC24XX_I2CONCLR);
writel(0, i2c->base + LPC24XX_I2ADDR);
writel(LPC24XX_I2EN, i2c->base + LPC24XX_I2CONSET);
}
static int i2c_lpc2k_clear_arb(struct lpc2k_i2c *i2c)
{
unsigned long timeout = jiffies + msecs_to_jiffies(1000);
/*
* If the transfer needs to abort for some reason, we'll try to
* force a stop condition to clear any pending bus conditions
*/
writel(LPC24XX_STO, i2c->base + LPC24XX_I2CONSET);
/* Wait for status change */
while (readl(i2c->base + LPC24XX_I2STAT) != M_I2C_IDLE) {
if (time_after(jiffies, timeout)) {
/* Bus was not idle, try to reset adapter */
i2c_lpc2k_reset(i2c);
return -EBUSY;
}
cpu_relax();
}
return 0;
}
static void i2c_lpc2k_pump_msg(struct lpc2k_i2c *i2c)
{
unsigned char data;
u32 status;
/*
* I2C in the LPC2xxx series is basically a state machine.
* Just run through the steps based on the current status.
*/
status = readl(i2c->base + LPC24XX_I2STAT);
switch (status) {
case M_START:
case M_REPSTART:
/* Start bit was just sent out, send out addr and dir */
data = i2c_8bit_addr_from_msg(i2c->msg);
writel(data, i2c->base + LPC24XX_I2DAT);
writel(LPC24XX_STA, i2c->base + LPC24XX_I2CONCLR);
break;
case MX_ADDR_W_ACK:
case MX_DATA_W_ACK:
/*
* Address or data was sent out with an ACK. If there is more
* data to send, send it now
*/
if (i2c->msg_idx < i2c->msg->len) {
writel(i2c->msg->buf[i2c->msg_idx],
i2c->base + LPC24XX_I2DAT);
} else if (i2c->is_last) {
/* Last message, send stop */
writel(LPC24XX_STO_AA, i2c->base + LPC24XX_I2CONSET);
writel(LPC24XX_SI, i2c->base + LPC24XX_I2CONCLR);
i2c->msg_status = 0;
disable_irq_nosync(i2c->irq);
} else {
i2c->msg_status = 0;
disable_irq_nosync(i2c->irq);
}
i2c->msg_idx++;
break;
case MR_ADDR_R_ACK:
/* Receive first byte from slave */
if (i2c->msg->len == 1) {
/* Last byte, return NACK */
writel(LPC24XX_AA, i2c->base + LPC24XX_I2CONCLR);
} else {
/* Not last byte, return ACK */
writel(LPC24XX_AA, i2c->base + LPC24XX_I2CONSET);
}
writel(LPC24XX_STA, i2c->base + LPC24XX_I2CONCLR);
break;
case MR_DATA_R_NACK:
/*
* The I2C shows NACK status on reads, so we need to accept
* the NACK as an ACK here. This should be ok, as the real
* BACK would of been caught on the address write.
*/
case MR_DATA_R_ACK:
/* Data was received */
if (i2c->msg_idx < i2c->msg->len) {
i2c->msg->buf[i2c->msg_idx] =
readl(i2c->base + LPC24XX_I2DAT);
}
/* If transfer is done, send STOP */
if (i2c->msg_idx >= i2c->msg->len - 1 && i2c->is_last) {
writel(LPC24XX_STO_AA, i2c->base + LPC24XX_I2CONSET);
writel(LPC24XX_SI, i2c->base + LPC24XX_I2CONCLR);
i2c->msg_status = 0;
}
/* Message is done */
if (i2c->msg_idx >= i2c->msg->len - 1) {
i2c->msg_status = 0;
disable_irq_nosync(i2c->irq);
}
/*
* One pre-last data input, send NACK to tell the slave that
* this is going to be the last data byte to be transferred.
*/
if (i2c->msg_idx >= i2c->msg->len - 2) {
/* One byte left to receive - NACK */
writel(LPC24XX_AA, i2c->base + LPC24XX_I2CONCLR);
} else {
/* More than one byte left to receive - ACK */
writel(LPC24XX_AA, i2c->base + LPC24XX_I2CONSET);
}
writel(LPC24XX_STA, i2c->base + LPC24XX_I2CONCLR);
i2c->msg_idx++;
break;
case MX_ADDR_W_NACK:
case MX_DATA_W_NACK:
case MR_ADDR_R_NACK:
/* NACK processing is done */
writel(LPC24XX_STO_AA, i2c->base + LPC24XX_I2CONSET);
i2c->msg_status = -ENXIO;
disable_irq_nosync(i2c->irq);
break;
case M_DATA_ARB_LOST:
/* Arbitration lost */
i2c->msg_status = -EAGAIN;
/* Release the I2C bus */
writel(LPC24XX_STA | LPC24XX_STO, i2c->base + LPC24XX_I2CONCLR);
disable_irq_nosync(i2c->irq);
break;
default:
/* Unexpected statuses */
i2c->msg_status = -EIO;
disable_irq_nosync(i2c->irq);
break;
}
/* Exit on failure or all bytes transferred */
if (i2c->msg_status != -EBUSY)
wake_up(&i2c->wait);
/*
* If `msg_status` is zero, then `lpc2k_process_msg()`
* is responsible for clearing the SI flag.
*/
if (i2c->msg_status != 0)
writel(LPC24XX_SI, i2c->base + LPC24XX_I2CONCLR);
}
static int lpc2k_process_msg(struct lpc2k_i2c *i2c, int msgidx)
{
/* A new transfer is kicked off by initiating a start condition */
if (!msgidx) {
writel(LPC24XX_STA, i2c->base + LPC24XX_I2CONSET);
} else {
/*
* A multi-message I2C transfer continues where the
* previous I2C transfer left off and uses the
* current condition of the I2C adapter.
*/
if (unlikely(i2c->msg->flags & I2C_M_NOSTART)) {
WARN_ON(i2c->msg->len == 0);
if (!(i2c->msg->flags & I2C_M_RD)) {
/* Start transmit of data */
writel(i2c->msg->buf[0],
i2c->base + LPC24XX_I2DAT);
i2c->msg_idx++;
}
} else {
/* Start or repeated start */
writel(LPC24XX_STA, i2c->base + LPC24XX_I2CONSET);
}
writel(LPC24XX_SI, i2c->base + LPC24XX_I2CONCLR);
}
enable_irq(i2c->irq);
/* Wait for transfer completion */
if (wait_event_timeout(i2c->wait, i2c->msg_status != -EBUSY,
msecs_to_jiffies(1000)) == 0) {
disable_irq_nosync(i2c->irq);
return -ETIMEDOUT;
}
return i2c->msg_status;
}
static int i2c_lpc2k_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
int msg_num)
{
struct lpc2k_i2c *i2c = i2c_get_adapdata(adap);
int ret, i;
u32 stat;
/* Check for bus idle condition */
stat = readl(i2c->base + LPC24XX_I2STAT);
if (stat != M_I2C_IDLE) {
/* Something is holding the bus, try to clear it */
return i2c_lpc2k_clear_arb(i2c);
}
/* Process a single message at a time */
for (i = 0; i < msg_num; i++) {
/* Save message pointer and current message data index */
i2c->msg = &msgs[i];
i2c->msg_idx = 0;
i2c->msg_status = -EBUSY;
i2c->is_last = (i == (msg_num - 1));
ret = lpc2k_process_msg(i2c, i);
if (ret)
return ret;
}
return msg_num;
}
static irqreturn_t i2c_lpc2k_handler(int irq, void *dev_id)
{
struct lpc2k_i2c *i2c = dev_id;
if (readl(i2c->base + LPC24XX_I2CONSET) & LPC24XX_SI) {
i2c_lpc2k_pump_msg(i2c);
return IRQ_HANDLED;
}
return IRQ_NONE;
}
static u32 i2c_lpc2k_functionality(struct i2c_adapter *adap)
{
/* Only emulated SMBus for now */
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}
static const struct i2c_algorithm i2c_lpc2k_algorithm = {
.master_xfer = i2c_lpc2k_xfer,
.functionality = i2c_lpc2k_functionality,
};
static int i2c_lpc2k_probe(struct platform_device *pdev)
{
struct lpc2k_i2c *i2c;
struct resource *res;
u32 bus_clk_rate;
u32 scl_high;
u32 clkrate;
int ret;
i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
if (!i2c)
return -ENOMEM;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
i2c->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(i2c->base))
return PTR_ERR(i2c->base);
i2c->irq = platform_get_irq(pdev, 0);
if (i2c->irq < 0) {
dev_err(&pdev->dev, "can't get interrupt resource\n");
return i2c->irq;
}
init_waitqueue_head(&i2c->wait);
i2c->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(i2c->clk)) {
dev_err(&pdev->dev, "error getting clock\n");
return PTR_ERR(i2c->clk);
}
ret = clk_prepare_enable(i2c->clk);
if (ret) {
dev_err(&pdev->dev, "unable to enable clock.\n");
return ret;
}
ret = devm_request_irq(&pdev->dev, i2c->irq, i2c_lpc2k_handler, 0,
dev_name(&pdev->dev), i2c);
if (ret < 0) {
dev_err(&pdev->dev, "can't request interrupt.\n");
goto fail_clk;
}
disable_irq_nosync(i2c->irq);
/* Place controller is a known state */
i2c_lpc2k_reset(i2c);
ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency",
&bus_clk_rate);
if (ret)
bus_clk_rate = 100000; /* 100 kHz default clock rate */
clkrate = clk_get_rate(i2c->clk);
if (clkrate == 0) {
dev_err(&pdev->dev, "can't get I2C base clock\n");
ret = -EINVAL;
goto fail_clk;
}
/* Setup I2C dividers to generate clock with proper duty cycle */
clkrate = clkrate / bus_clk_rate;
if (bus_clk_rate <= 100000)
scl_high = (clkrate * I2C_STD_MODE_DUTY) / 100;
else if (bus_clk_rate <= 400000)
scl_high = (clkrate * I2C_FAST_MODE_DUTY) / 100;
else
scl_high = (clkrate * I2C_FAST_MODE_PLUS_DUTY) / 100;
writel(scl_high, i2c->base + LPC24XX_I2SCLH);
writel(clkrate - scl_high, i2c->base + LPC24XX_I2SCLL);
platform_set_drvdata(pdev, i2c);
i2c_set_adapdata(&i2c->adap, i2c);
i2c->adap.owner = THIS_MODULE;
strlcpy(i2c->adap.name, "LPC2K I2C adapter", sizeof(i2c->adap.name));
i2c->adap.algo = &i2c_lpc2k_algorithm;
i2c->adap.dev.parent = &pdev->dev;
i2c->adap.dev.of_node = pdev->dev.of_node;
ret = i2c_add_adapter(&i2c->adap);
if (ret < 0)
goto fail_clk;
dev_info(&pdev->dev, "LPC2K I2C adapter\n");
return 0;
fail_clk:
clk_disable_unprepare(i2c->clk);
return ret;
}
static int i2c_lpc2k_remove(struct platform_device *dev)
{
struct lpc2k_i2c *i2c = platform_get_drvdata(dev);
i2c_del_adapter(&i2c->adap);
clk_disable_unprepare(i2c->clk);
return 0;
}
#ifdef CONFIG_PM
static int i2c_lpc2k_suspend(struct device *dev)
{
struct lpc2k_i2c *i2c = dev_get_drvdata(dev);
clk_disable(i2c->clk);
return 0;
}
static int i2c_lpc2k_resume(struct device *dev)
{
struct lpc2k_i2c *i2c = dev_get_drvdata(dev);
clk_enable(i2c->clk);
i2c_lpc2k_reset(i2c);
return 0;
}
static const struct dev_pm_ops i2c_lpc2k_dev_pm_ops = {
.suspend_noirq = i2c_lpc2k_suspend,
.resume_noirq = i2c_lpc2k_resume,
};
#define I2C_LPC2K_DEV_PM_OPS (&i2c_lpc2k_dev_pm_ops)
#else
#define I2C_LPC2K_DEV_PM_OPS NULL
#endif
static const struct of_device_id lpc2k_i2c_match[] = {
{ .compatible = "nxp,lpc1788-i2c" },
{},
};
MODULE_DEVICE_TABLE(of, lpc2k_i2c_match);
static struct platform_driver i2c_lpc2k_driver = {
.probe = i2c_lpc2k_probe,
.remove = i2c_lpc2k_remove,
.driver = {
.name = "lpc2k-i2c",
.pm = I2C_LPC2K_DEV_PM_OPS,
.of_match_table = lpc2k_i2c_match,
},
};
module_platform_driver(i2c_lpc2k_driver);
MODULE_AUTHOR("Kevin Wells <kevin.wells@nxp.com>");
MODULE_DESCRIPTION("I2C driver for LPC2xxx devices");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:lpc2k-i2c");
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