linux/drivers/i2c/busses/i2c-rcar.c
Wolfram Sang 5b77d162a3 i2c: slave: rework the slave API
After more discussion, brave users, and additional datasheet evaluation,
some API updates for the new I2C slave framework became imminent. The
slave events now get some easier to understand naming. Also, the event
handling has been simplified to only need a single call to the slave
callback when an action by the backend is required.

Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
2015-03-27 16:53:38 +01:00

739 lines
18 KiB
C

/*
* Driver for the Renesas RCar I2C unit
*
* Copyright (C) 2014 Wolfram Sang <wsa@sang-engineering.com>
*
* Copyright (C) 2012-14 Renesas Solutions Corp.
* Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
*
* This file is based on the drivers/i2c/busses/i2c-sh7760.c
* (c) 2005-2008 MSC Vertriebsges.m.b.H, Manuel Lauss <mlau@msc-ge.com>
*
* This file used out-of-tree driver i2c-rcar.c
* Copyright (C) 2011-2012 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 as published by
* the Free Software Foundation; version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/i2c.h>
#include <linux/i2c/i2c-rcar.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
/* register offsets */
#define ICSCR 0x00 /* slave ctrl */
#define ICMCR 0x04 /* master ctrl */
#define ICSSR 0x08 /* slave status */
#define ICMSR 0x0C /* master status */
#define ICSIER 0x10 /* slave irq enable */
#define ICMIER 0x14 /* master irq enable */
#define ICCCR 0x18 /* clock dividers */
#define ICSAR 0x1C /* slave address */
#define ICMAR 0x20 /* master address */
#define ICRXTX 0x24 /* data port */
/* ICSCR */
#define SDBS (1 << 3) /* slave data buffer select */
#define SIE (1 << 2) /* slave interface enable */
#define GCAE (1 << 1) /* general call address enable */
#define FNA (1 << 0) /* forced non acknowledgment */
/* ICMCR */
#define MDBS (1 << 7) /* non-fifo mode switch */
#define FSCL (1 << 6) /* override SCL pin */
#define FSDA (1 << 5) /* override SDA pin */
#define OBPC (1 << 4) /* override pins */
#define MIE (1 << 3) /* master if enable */
#define TSBE (1 << 2)
#define FSB (1 << 1) /* force stop bit */
#define ESG (1 << 0) /* en startbit gen */
/* ICSSR (also for ICSIER) */
#define GCAR (1 << 6) /* general call received */
#define STM (1 << 5) /* slave transmit mode */
#define SSR (1 << 4) /* stop received */
#define SDE (1 << 3) /* slave data empty */
#define SDT (1 << 2) /* slave data transmitted */
#define SDR (1 << 1) /* slave data received */
#define SAR (1 << 0) /* slave addr received */
/* ICMSR (also for ICMIE) */
#define MNR (1 << 6) /* nack received */
#define MAL (1 << 5) /* arbitration lost */
#define MST (1 << 4) /* sent a stop */
#define MDE (1 << 3)
#define MDT (1 << 2)
#define MDR (1 << 1)
#define MAT (1 << 0) /* slave addr xfer done */
#define RCAR_BUS_PHASE_START (MDBS | MIE | ESG)
#define RCAR_BUS_PHASE_DATA (MDBS | MIE)
#define RCAR_BUS_PHASE_STOP (MDBS | MIE | FSB)
#define RCAR_IRQ_SEND (MNR | MAL | MST | MAT | MDE)
#define RCAR_IRQ_RECV (MNR | MAL | MST | MAT | MDR)
#define RCAR_IRQ_STOP (MST)
#define RCAR_IRQ_ACK_SEND (~(MAT | MDE) & 0xFF)
#define RCAR_IRQ_ACK_RECV (~(MAT | MDR) & 0xFF)
#define ID_LAST_MSG (1 << 0)
#define ID_IOERROR (1 << 1)
#define ID_DONE (1 << 2)
#define ID_ARBLOST (1 << 3)
#define ID_NACK (1 << 4)
enum rcar_i2c_type {
I2C_RCAR_GEN1,
I2C_RCAR_GEN2,
};
struct rcar_i2c_priv {
void __iomem *io;
struct i2c_adapter adap;
struct i2c_msg *msg;
struct clk *clk;
spinlock_t lock;
wait_queue_head_t wait;
int pos;
u32 icccr;
u32 flags;
enum rcar_i2c_type devtype;
struct i2c_client *slave;
};
#define rcar_i2c_priv_to_dev(p) ((p)->adap.dev.parent)
#define rcar_i2c_is_recv(p) ((p)->msg->flags & I2C_M_RD)
#define rcar_i2c_flags_set(p, f) ((p)->flags |= (f))
#define rcar_i2c_flags_has(p, f) ((p)->flags & (f))
#define LOOP_TIMEOUT 1024
static void rcar_i2c_write(struct rcar_i2c_priv *priv, int reg, u32 val)
{
writel(val, priv->io + reg);
}
static u32 rcar_i2c_read(struct rcar_i2c_priv *priv, int reg)
{
return readl(priv->io + reg);
}
static void rcar_i2c_init(struct rcar_i2c_priv *priv)
{
/* reset master mode */
rcar_i2c_write(priv, ICMIER, 0);
rcar_i2c_write(priv, ICMCR, 0);
rcar_i2c_write(priv, ICMSR, 0);
rcar_i2c_write(priv, ICMAR, 0);
}
static int rcar_i2c_bus_barrier(struct rcar_i2c_priv *priv)
{
int i;
for (i = 0; i < LOOP_TIMEOUT; i++) {
/* make sure that bus is not busy */
if (!(rcar_i2c_read(priv, ICMCR) & FSDA))
return 0;
udelay(1);
}
return -EBUSY;
}
static int rcar_i2c_clock_calculate(struct rcar_i2c_priv *priv,
u32 bus_speed,
struct device *dev)
{
u32 scgd, cdf;
u32 round, ick;
u32 scl;
u32 cdf_width;
unsigned long rate;
switch (priv->devtype) {
case I2C_RCAR_GEN1:
cdf_width = 2;
break;
case I2C_RCAR_GEN2:
cdf_width = 3;
break;
default:
dev_err(dev, "device type error\n");
return -EIO;
}
/*
* calculate SCL clock
* see
* ICCCR
*
* ick = clkp / (1 + CDF)
* SCL = ick / (20 + SCGD * 8 + F[(ticf + tr + intd) * ick])
*
* ick : I2C internal clock < 20 MHz
* ticf : I2C SCL falling time = 35 ns here
* tr : I2C SCL rising time = 200 ns here
* intd : LSI internal delay = 50 ns here
* clkp : peripheral_clk
* F[] : integer up-valuation
*/
rate = clk_get_rate(priv->clk);
cdf = rate / 20000000;
if (cdf >= 1U << cdf_width) {
dev_err(dev, "Input clock %lu too high\n", rate);
return -EIO;
}
ick = rate / (cdf + 1);
/*
* it is impossible to calculate large scale
* number on u32. separate it
*
* F[(ticf + tr + intd) * ick]
* = F[(35 + 200 + 50)ns * ick]
* = F[285 * ick / 1000000000]
* = F[(ick / 1000000) * 285 / 1000]
*/
round = (ick + 500000) / 1000000 * 285;
round = (round + 500) / 1000;
/*
* SCL = ick / (20 + SCGD * 8 + F[(ticf + tr + intd) * ick])
*
* Calculation result (= SCL) should be less than
* bus_speed for hardware safety
*
* We could use something along the lines of
* div = ick / (bus_speed + 1) + 1;
* scgd = (div - 20 - round + 7) / 8;
* scl = ick / (20 + (scgd * 8) + round);
* (not fully verified) but that would get pretty involved
*/
for (scgd = 0; scgd < 0x40; scgd++) {
scl = ick / (20 + (scgd * 8) + round);
if (scl <= bus_speed)
goto scgd_find;
}
dev_err(dev, "it is impossible to calculate best SCL\n");
return -EIO;
scgd_find:
dev_dbg(dev, "clk %d/%d(%lu), round %u, CDF:0x%x, SCGD: 0x%x\n",
scl, bus_speed, clk_get_rate(priv->clk), round, cdf, scgd);
/*
* keep icccr value
*/
priv->icccr = scgd << cdf_width | cdf;
return 0;
}
static void rcar_i2c_prepare_msg(struct rcar_i2c_priv *priv)
{
int read = !!rcar_i2c_is_recv(priv);
rcar_i2c_write(priv, ICMAR, (priv->msg->addr << 1) | read);
rcar_i2c_write(priv, ICMSR, 0);
rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_START);
rcar_i2c_write(priv, ICMIER, read ? RCAR_IRQ_RECV : RCAR_IRQ_SEND);
}
/*
* interrupt functions
*/
static int rcar_i2c_irq_send(struct rcar_i2c_priv *priv, u32 msr)
{
struct i2c_msg *msg = priv->msg;
/*
* FIXME
* sometimes, unknown interrupt happened.
* Do nothing
*/
if (!(msr & MDE))
return 0;
/*
* If address transfer phase finished,
* goto data phase.
*/
if (msr & MAT)
rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA);
if (priv->pos < msg->len) {
/*
* Prepare next data to ICRXTX register.
* This data will go to _SHIFT_ register.
*
* *
* [ICRXTX] -> [SHIFT] -> [I2C bus]
*/
rcar_i2c_write(priv, ICRXTX, msg->buf[priv->pos]);
priv->pos++;
} else {
/*
* The last data was pushed to ICRXTX on _PREV_ empty irq.
* It is on _SHIFT_ register, and will sent to I2C bus.
*
* *
* [ICRXTX] -> [SHIFT] -> [I2C bus]
*/
if (priv->flags & ID_LAST_MSG)
/*
* If current msg is the _LAST_ msg,
* prepare stop condition here.
* ID_DONE will be set on STOP irq.
*/
rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_STOP);
else
/*
* If current msg is _NOT_ last msg,
* it doesn't call stop phase.
* thus, there is no STOP irq.
* return ID_DONE here.
*/
return ID_DONE;
}
rcar_i2c_write(priv, ICMSR, RCAR_IRQ_ACK_SEND);
return 0;
}
static int rcar_i2c_irq_recv(struct rcar_i2c_priv *priv, u32 msr)
{
struct i2c_msg *msg = priv->msg;
/*
* FIXME
* sometimes, unknown interrupt happened.
* Do nothing
*/
if (!(msr & MDR))
return 0;
if (msr & MAT) {
/*
* Address transfer phase finished,
* but, there is no data at this point.
* Do nothing.
*/
} else if (priv->pos < msg->len) {
/*
* get received data
*/
msg->buf[priv->pos] = rcar_i2c_read(priv, ICRXTX);
priv->pos++;
}
/*
* If next received data is the _LAST_,
* go to STOP phase,
* otherwise, go to DATA phase.
*/
if (priv->pos + 1 >= msg->len)
rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_STOP);
else
rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA);
rcar_i2c_write(priv, ICMSR, RCAR_IRQ_ACK_RECV);
return 0;
}
static bool rcar_i2c_slave_irq(struct rcar_i2c_priv *priv)
{
u32 ssr_raw, ssr_filtered;
u8 value;
ssr_raw = rcar_i2c_read(priv, ICSSR) & 0xff;
ssr_filtered = ssr_raw & rcar_i2c_read(priv, ICSIER);
if (!ssr_filtered)
return false;
/* address detected */
if (ssr_filtered & SAR) {
/* read or write request */
if (ssr_raw & STM) {
i2c_slave_event(priv->slave, I2C_SLAVE_READ_REQUESTED, &value);
rcar_i2c_write(priv, ICRXTX, value);
rcar_i2c_write(priv, ICSIER, SDE | SSR | SAR);
} else {
i2c_slave_event(priv->slave, I2C_SLAVE_WRITE_REQUESTED, &value);
rcar_i2c_read(priv, ICRXTX); /* dummy read */
rcar_i2c_write(priv, ICSIER, SDR | SSR | SAR);
}
rcar_i2c_write(priv, ICSSR, ~SAR & 0xff);
}
/* master sent stop */
if (ssr_filtered & SSR) {
i2c_slave_event(priv->slave, I2C_SLAVE_STOP, &value);
rcar_i2c_write(priv, ICSIER, SAR | SSR);
rcar_i2c_write(priv, ICSSR, ~SSR & 0xff);
}
/* master wants to write to us */
if (ssr_filtered & SDR) {
int ret;
value = rcar_i2c_read(priv, ICRXTX);
ret = i2c_slave_event(priv->slave, I2C_SLAVE_WRITE_RECEIVED, &value);
/* Send NACK in case of error */
rcar_i2c_write(priv, ICSCR, SIE | SDBS | (ret < 0 ? FNA : 0));
rcar_i2c_write(priv, ICSSR, ~SDR & 0xff);
}
/* master wants to read from us */
if (ssr_filtered & SDE) {
i2c_slave_event(priv->slave, I2C_SLAVE_READ_PROCESSED, &value);
rcar_i2c_write(priv, ICRXTX, value);
rcar_i2c_write(priv, ICSSR, ~SDE & 0xff);
}
return true;
}
static irqreturn_t rcar_i2c_irq(int irq, void *ptr)
{
struct rcar_i2c_priv *priv = ptr;
irqreturn_t result = IRQ_HANDLED;
u32 msr;
/*-------------- spin lock -----------------*/
spin_lock(&priv->lock);
if (rcar_i2c_slave_irq(priv))
goto exit;
msr = rcar_i2c_read(priv, ICMSR);
/* Only handle interrupts that are currently enabled */
msr &= rcar_i2c_read(priv, ICMIER);
if (!msr) {
result = IRQ_NONE;
goto exit;
}
/* Arbitration lost */
if (msr & MAL) {
rcar_i2c_flags_set(priv, (ID_DONE | ID_ARBLOST));
goto out;
}
/* Nack */
if (msr & MNR) {
/* go to stop phase */
rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_STOP);
rcar_i2c_write(priv, ICMIER, RCAR_IRQ_STOP);
rcar_i2c_flags_set(priv, ID_NACK);
goto out;
}
/* Stop */
if (msr & MST) {
rcar_i2c_flags_set(priv, ID_DONE);
goto out;
}
if (rcar_i2c_is_recv(priv))
rcar_i2c_flags_set(priv, rcar_i2c_irq_recv(priv, msr));
else
rcar_i2c_flags_set(priv, rcar_i2c_irq_send(priv, msr));
out:
if (rcar_i2c_flags_has(priv, ID_DONE)) {
rcar_i2c_write(priv, ICMIER, 0);
rcar_i2c_write(priv, ICMSR, 0);
wake_up(&priv->wait);
}
exit:
spin_unlock(&priv->lock);
/*-------------- spin unlock -----------------*/
return result;
}
static int rcar_i2c_master_xfer(struct i2c_adapter *adap,
struct i2c_msg *msgs,
int num)
{
struct rcar_i2c_priv *priv = i2c_get_adapdata(adap);
struct device *dev = rcar_i2c_priv_to_dev(priv);
unsigned long flags;
int i, ret, timeout;
pm_runtime_get_sync(dev);
/*-------------- spin lock -----------------*/
spin_lock_irqsave(&priv->lock, flags);
rcar_i2c_init(priv);
/* start clock */
rcar_i2c_write(priv, ICCCR, priv->icccr);
spin_unlock_irqrestore(&priv->lock, flags);
/*-------------- spin unlock -----------------*/
ret = rcar_i2c_bus_barrier(priv);
if (ret < 0)
goto out;
for (i = 0; i < num; i++) {
/* This HW can't send STOP after address phase */
if (msgs[i].len == 0) {
ret = -EOPNOTSUPP;
break;
}
/*-------------- spin lock -----------------*/
spin_lock_irqsave(&priv->lock, flags);
/* init each data */
priv->msg = &msgs[i];
priv->pos = 0;
priv->flags = 0;
if (i == num - 1)
rcar_i2c_flags_set(priv, ID_LAST_MSG);
rcar_i2c_prepare_msg(priv);
spin_unlock_irqrestore(&priv->lock, flags);
/*-------------- spin unlock -----------------*/
timeout = wait_event_timeout(priv->wait,
rcar_i2c_flags_has(priv, ID_DONE),
5 * HZ);
if (!timeout) {
ret = -ETIMEDOUT;
break;
}
if (rcar_i2c_flags_has(priv, ID_NACK)) {
ret = -ENXIO;
break;
}
if (rcar_i2c_flags_has(priv, ID_ARBLOST)) {
ret = -EAGAIN;
break;
}
if (rcar_i2c_flags_has(priv, ID_IOERROR)) {
ret = -EIO;
break;
}
ret = i + 1; /* The number of transfer */
}
out:
pm_runtime_put(dev);
if (ret < 0 && ret != -ENXIO)
dev_err(dev, "error %d : %x\n", ret, priv->flags);
return ret;
}
static int rcar_reg_slave(struct i2c_client *slave)
{
struct rcar_i2c_priv *priv = i2c_get_adapdata(slave->adapter);
if (priv->slave)
return -EBUSY;
if (slave->flags & I2C_CLIENT_TEN)
return -EAFNOSUPPORT;
pm_runtime_forbid(rcar_i2c_priv_to_dev(priv));
priv->slave = slave;
rcar_i2c_write(priv, ICSAR, slave->addr);
rcar_i2c_write(priv, ICSSR, 0);
rcar_i2c_write(priv, ICSIER, SAR | SSR);
rcar_i2c_write(priv, ICSCR, SIE | SDBS);
return 0;
}
static int rcar_unreg_slave(struct i2c_client *slave)
{
struct rcar_i2c_priv *priv = i2c_get_adapdata(slave->adapter);
WARN_ON(!priv->slave);
rcar_i2c_write(priv, ICSIER, 0);
rcar_i2c_write(priv, ICSCR, 0);
priv->slave = NULL;
pm_runtime_allow(rcar_i2c_priv_to_dev(priv));
return 0;
}
static u32 rcar_i2c_func(struct i2c_adapter *adap)
{
/* This HW can't do SMBUS_QUICK and NOSTART */
return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
}
static const struct i2c_algorithm rcar_i2c_algo = {
.master_xfer = rcar_i2c_master_xfer,
.functionality = rcar_i2c_func,
.reg_slave = rcar_reg_slave,
.unreg_slave = rcar_unreg_slave,
};
static const struct of_device_id rcar_i2c_dt_ids[] = {
{ .compatible = "renesas,i2c-rcar", .data = (void *)I2C_RCAR_GEN1 },
{ .compatible = "renesas,i2c-r8a7778", .data = (void *)I2C_RCAR_GEN1 },
{ .compatible = "renesas,i2c-r8a7779", .data = (void *)I2C_RCAR_GEN1 },
{ .compatible = "renesas,i2c-r8a7790", .data = (void *)I2C_RCAR_GEN2 },
{ .compatible = "renesas,i2c-r8a7791", .data = (void *)I2C_RCAR_GEN2 },
{ .compatible = "renesas,i2c-r8a7792", .data = (void *)I2C_RCAR_GEN2 },
{ .compatible = "renesas,i2c-r8a7793", .data = (void *)I2C_RCAR_GEN2 },
{ .compatible = "renesas,i2c-r8a7794", .data = (void *)I2C_RCAR_GEN2 },
{},
};
MODULE_DEVICE_TABLE(of, rcar_i2c_dt_ids);
static int rcar_i2c_probe(struct platform_device *pdev)
{
struct i2c_rcar_platform_data *pdata = dev_get_platdata(&pdev->dev);
struct rcar_i2c_priv *priv;
struct i2c_adapter *adap;
struct resource *res;
struct device *dev = &pdev->dev;
u32 bus_speed;
int irq, ret;
priv = devm_kzalloc(dev, sizeof(struct rcar_i2c_priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
priv->clk = devm_clk_get(dev, NULL);
if (IS_ERR(priv->clk)) {
dev_err(dev, "cannot get clock\n");
return PTR_ERR(priv->clk);
}
bus_speed = 100000; /* default 100 kHz */
ret = of_property_read_u32(dev->of_node, "clock-frequency", &bus_speed);
if (ret < 0 && pdata && pdata->bus_speed)
bus_speed = pdata->bus_speed;
if (pdev->dev.of_node)
priv->devtype = (long)of_match_device(rcar_i2c_dt_ids,
dev)->data;
else
priv->devtype = platform_get_device_id(pdev)->driver_data;
ret = rcar_i2c_clock_calculate(priv, bus_speed, dev);
if (ret < 0)
return ret;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
priv->io = devm_ioremap_resource(dev, res);
if (IS_ERR(priv->io))
return PTR_ERR(priv->io);
irq = platform_get_irq(pdev, 0);
init_waitqueue_head(&priv->wait);
spin_lock_init(&priv->lock);
adap = &priv->adap;
adap->nr = pdev->id;
adap->algo = &rcar_i2c_algo;
adap->class = I2C_CLASS_DEPRECATED;
adap->retries = 3;
adap->dev.parent = dev;
adap->dev.of_node = dev->of_node;
i2c_set_adapdata(adap, priv);
strlcpy(adap->name, pdev->name, sizeof(adap->name));
ret = devm_request_irq(dev, irq, rcar_i2c_irq, 0,
dev_name(dev), priv);
if (ret < 0) {
dev_err(dev, "cannot get irq %d\n", irq);
return ret;
}
ret = i2c_add_numbered_adapter(adap);
if (ret < 0) {
dev_err(dev, "reg adap failed: %d\n", ret);
return ret;
}
pm_runtime_enable(dev);
platform_set_drvdata(pdev, priv);
dev_info(dev, "probed\n");
return 0;
}
static int rcar_i2c_remove(struct platform_device *pdev)
{
struct rcar_i2c_priv *priv = platform_get_drvdata(pdev);
struct device *dev = &pdev->dev;
i2c_del_adapter(&priv->adap);
pm_runtime_disable(dev);
return 0;
}
static struct platform_device_id rcar_i2c_id_table[] = {
{ "i2c-rcar", I2C_RCAR_GEN1 },
{ "i2c-rcar_gen1", I2C_RCAR_GEN1 },
{ "i2c-rcar_gen2", I2C_RCAR_GEN2 },
{},
};
MODULE_DEVICE_TABLE(platform, rcar_i2c_id_table);
static struct platform_driver rcar_i2c_driver = {
.driver = {
.name = "i2c-rcar",
.of_match_table = rcar_i2c_dt_ids,
},
.probe = rcar_i2c_probe,
.remove = rcar_i2c_remove,
.id_table = rcar_i2c_id_table,
};
module_platform_driver(rcar_i2c_driver);
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Renesas R-Car I2C bus driver");
MODULE_AUTHOR("Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>");