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linux/drivers/i2c/busses/i2c-xiic.c
Jaakko Laine 9e3b184b3b i2c: xiic: Support forcing single-master in DT 
I2C master operating in multimaster mode can get stuck
indefinitely if I2C start is detected on bus, but no master
has a transaction going.

This is a weakness in I2C standard, which defines no way
to recover, since all masters are indefinitely disallowed
from interrupting the currently operating master. A start
condition can be created for example by an electromagnetic
discharge applied near physical I2C lines. Or a already
operating master could get reset immediately after sending
a start.

If it is known during device tree creation that only a single
I2C master will be present on the bus, this deadlock of the
I2C bus could be avoided in the driver by ignoring the
bus_is_busy register of the xiic, since bus can never be
reserved by any other master.

This patch adds this support for detecting single-master flag
in device tree and when provided, improves I2C reliability by
ignoring the therefore unnecessary xiic bus_is_busy register.

Error can be reproduced by pulling I2C SDA -line temporarily low
by shorting it to ground, while linux I2C master is operating on
it using the xiic driver. The application using the bus will
start receiving linux error code 16: "Device or resource busy"
indefinitely:

kernel: pca953x 0-0020: failed writing register
app: Error writing file, error: 16

With multi-master disabled device will instead receive error
code 5: "I/O error" while SDA is grounded, but recover normal
operation once short is removed.

kernel: pca953x 0-0020: failed reading register
app: Error reading file, error: 5

Signed-off-by: Jaakko Laine <ext-jaakko.laine@vaisala.com>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
2020-08-28 09:00:00 +02:00

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// SPDX-License-Identifier: GPL-2.0-only
/*
* i2c-xiic.c
* Copyright (c) 2002-2007 Xilinx Inc.
* Copyright (c) 2009-2010 Intel Corporation
*
* This code was implemented by Mocean Laboratories AB when porting linux
* to the automotive development board Russellville. The copyright holder
* as seen in the header is Intel corporation.
* Mocean Laboratories forked off the GNU/Linux platform work into a
* separate company called Pelagicore AB, which committed the code to the
* kernel.
*/
/* Supports:
* Xilinx IIC
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/wait.h>
#include <linux/platform_data/i2c-xiic.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/clk.h>
#include <linux/pm_runtime.h>
#define DRIVER_NAME "xiic-i2c"
enum xilinx_i2c_state {
STATE_DONE,
STATE_ERROR,
STATE_START
};
enum xiic_endian {
LITTLE,
BIG
};
/**
* struct xiic_i2c - Internal representation of the XIIC I2C bus
* @dev: Pointer to device structure
* @base: Memory base of the HW registers
* @wait: Wait queue for callers
* @adap: Kernel adapter representation
* @tx_msg: Messages from above to be sent
* @lock: Mutual exclusion
* @tx_pos: Current pos in TX message
* @nmsgs: Number of messages in tx_msg
* @rx_msg: Current RX message
* @rx_pos: Position within current RX message
* @endianness: big/little-endian byte order
* @clk: Pointer to AXI4-lite input clock
* @state: See STATE_
* @singlemaster: Indicates bus is single master
*/
struct xiic_i2c {
struct device *dev;
void __iomem *base;
wait_queue_head_t wait;
struct i2c_adapter adap;
struct i2c_msg *tx_msg;
struct mutex lock;
unsigned int tx_pos;
unsigned int nmsgs;
struct i2c_msg *rx_msg;
int rx_pos;
enum xiic_endian endianness;
struct clk *clk;
enum xilinx_i2c_state state;
bool singlemaster;
};
#define XIIC_MSB_OFFSET 0
#define XIIC_REG_OFFSET (0x100+XIIC_MSB_OFFSET)
/*
* Register offsets in bytes from RegisterBase. Three is added to the
* base offset to access LSB (IBM style) of the word
*/
#define XIIC_CR_REG_OFFSET (0x00+XIIC_REG_OFFSET) /* Control Register */
#define XIIC_SR_REG_OFFSET (0x04+XIIC_REG_OFFSET) /* Status Register */
#define XIIC_DTR_REG_OFFSET (0x08+XIIC_REG_OFFSET) /* Data Tx Register */
#define XIIC_DRR_REG_OFFSET (0x0C+XIIC_REG_OFFSET) /* Data Rx Register */
#define XIIC_ADR_REG_OFFSET (0x10+XIIC_REG_OFFSET) /* Address Register */
#define XIIC_TFO_REG_OFFSET (0x14+XIIC_REG_OFFSET) /* Tx FIFO Occupancy */
#define XIIC_RFO_REG_OFFSET (0x18+XIIC_REG_OFFSET) /* Rx FIFO Occupancy */
#define XIIC_TBA_REG_OFFSET (0x1C+XIIC_REG_OFFSET) /* 10 Bit Address reg */
#define XIIC_RFD_REG_OFFSET (0x20+XIIC_REG_OFFSET) /* Rx FIFO Depth reg */
#define XIIC_GPO_REG_OFFSET (0x24+XIIC_REG_OFFSET) /* Output Register */
/* Control Register masks */
#define XIIC_CR_ENABLE_DEVICE_MASK 0x01 /* Device enable = 1 */
#define XIIC_CR_TX_FIFO_RESET_MASK 0x02 /* Transmit FIFO reset=1 */
#define XIIC_CR_MSMS_MASK 0x04 /* Master starts Txing=1 */
#define XIIC_CR_DIR_IS_TX_MASK 0x08 /* Dir of tx. Txing=1 */
#define XIIC_CR_NO_ACK_MASK 0x10 /* Tx Ack. NO ack = 1 */
#define XIIC_CR_REPEATED_START_MASK 0x20 /* Repeated start = 1 */
#define XIIC_CR_GENERAL_CALL_MASK 0x40 /* Gen Call enabled = 1 */
/* Status Register masks */
#define XIIC_SR_GEN_CALL_MASK 0x01 /* 1=a mstr issued a GC */
#define XIIC_SR_ADDR_AS_SLAVE_MASK 0x02 /* 1=when addr as slave */
#define XIIC_SR_BUS_BUSY_MASK 0x04 /* 1 = bus is busy */
#define XIIC_SR_MSTR_RDING_SLAVE_MASK 0x08 /* 1=Dir: mstr <-- slave */
#define XIIC_SR_TX_FIFO_FULL_MASK 0x10 /* 1 = Tx FIFO full */
#define XIIC_SR_RX_FIFO_FULL_MASK 0x20 /* 1 = Rx FIFO full */
#define XIIC_SR_RX_FIFO_EMPTY_MASK 0x40 /* 1 = Rx FIFO empty */
#define XIIC_SR_TX_FIFO_EMPTY_MASK 0x80 /* 1 = Tx FIFO empty */
/* Interrupt Status Register masks Interrupt occurs when... */
#define XIIC_INTR_ARB_LOST_MASK 0x01 /* 1 = arbitration lost */
#define XIIC_INTR_TX_ERROR_MASK 0x02 /* 1=Tx error/msg complete */
#define XIIC_INTR_TX_EMPTY_MASK 0x04 /* 1 = Tx FIFO/reg empty */
#define XIIC_INTR_RX_FULL_MASK 0x08 /* 1=Rx FIFO/reg=OCY level */
#define XIIC_INTR_BNB_MASK 0x10 /* 1 = Bus not busy */
#define XIIC_INTR_AAS_MASK 0x20 /* 1 = when addr as slave */
#define XIIC_INTR_NAAS_MASK 0x40 /* 1 = not addr as slave */
#define XIIC_INTR_TX_HALF_MASK 0x80 /* 1 = TX FIFO half empty */
/* The following constants specify the depth of the FIFOs */
#define IIC_RX_FIFO_DEPTH 16 /* Rx fifo capacity */
#define IIC_TX_FIFO_DEPTH 16 /* Tx fifo capacity */
/* The following constants specify groups of interrupts that are typically
* enabled or disables at the same time
*/
#define XIIC_TX_INTERRUPTS \
(XIIC_INTR_TX_ERROR_MASK | XIIC_INTR_TX_EMPTY_MASK | XIIC_INTR_TX_HALF_MASK)
#define XIIC_TX_RX_INTERRUPTS (XIIC_INTR_RX_FULL_MASK | XIIC_TX_INTERRUPTS)
/*
* Tx Fifo upper bit masks.
*/
#define XIIC_TX_DYN_START_MASK 0x0100 /* 1 = Set dynamic start */
#define XIIC_TX_DYN_STOP_MASK 0x0200 /* 1 = Set dynamic stop */
/*
* The following constants define the register offsets for the Interrupt
* registers. There are some holes in the memory map for reserved addresses
* to allow other registers to be added and still match the memory map of the
* interrupt controller registers
*/
#define XIIC_DGIER_OFFSET 0x1C /* Device Global Interrupt Enable Register */
#define XIIC_IISR_OFFSET 0x20 /* Interrupt Status Register */
#define XIIC_IIER_OFFSET 0x28 /* Interrupt Enable Register */
#define XIIC_RESETR_OFFSET 0x40 /* Reset Register */
#define XIIC_RESET_MASK 0xAUL
#define XIIC_PM_TIMEOUT 1000 /* ms */
/* timeout waiting for the controller to respond */
#define XIIC_I2C_TIMEOUT (msecs_to_jiffies(1000))
/*
* The following constant is used for the device global interrupt enable
* register, to enable all interrupts for the device, this is the only bit
* in the register
*/
#define XIIC_GINTR_ENABLE_MASK 0x80000000UL
#define xiic_tx_space(i2c) ((i2c)->tx_msg->len - (i2c)->tx_pos)
#define xiic_rx_space(i2c) ((i2c)->rx_msg->len - (i2c)->rx_pos)
static int xiic_start_xfer(struct xiic_i2c *i2c);
static void __xiic_start_xfer(struct xiic_i2c *i2c);
/*
* For the register read and write functions, a little-endian and big-endian
* version are necessary. Endianness is detected during the probe function.
* Only the least significant byte [doublet] of the register are ever
* accessed. This requires an offset of 3 [2] from the base address for
* big-endian systems.
*/
static inline void xiic_setreg8(struct xiic_i2c *i2c, int reg, u8 value)
{
if (i2c->endianness == LITTLE)
iowrite8(value, i2c->base + reg);
else
iowrite8(value, i2c->base + reg + 3);
}
static inline u8 xiic_getreg8(struct xiic_i2c *i2c, int reg)
{
u8 ret;
if (i2c->endianness == LITTLE)
ret = ioread8(i2c->base + reg);
else
ret = ioread8(i2c->base + reg + 3);
return ret;
}
static inline void xiic_setreg16(struct xiic_i2c *i2c, int reg, u16 value)
{
if (i2c->endianness == LITTLE)
iowrite16(value, i2c->base + reg);
else
iowrite16be(value, i2c->base + reg + 2);
}
static inline void xiic_setreg32(struct xiic_i2c *i2c, int reg, int value)
{
if (i2c->endianness == LITTLE)
iowrite32(value, i2c->base + reg);
else
iowrite32be(value, i2c->base + reg);
}
static inline int xiic_getreg32(struct xiic_i2c *i2c, int reg)
{
u32 ret;
if (i2c->endianness == LITTLE)
ret = ioread32(i2c->base + reg);
else
ret = ioread32be(i2c->base + reg);
return ret;
}
static inline void xiic_irq_dis(struct xiic_i2c *i2c, u32 mask)
{
u32 ier = xiic_getreg32(i2c, XIIC_IIER_OFFSET);
xiic_setreg32(i2c, XIIC_IIER_OFFSET, ier & ~mask);
}
static inline void xiic_irq_en(struct xiic_i2c *i2c, u32 mask)
{
u32 ier = xiic_getreg32(i2c, XIIC_IIER_OFFSET);
xiic_setreg32(i2c, XIIC_IIER_OFFSET, ier | mask);
}
static inline void xiic_irq_clr(struct xiic_i2c *i2c, u32 mask)
{
u32 isr = xiic_getreg32(i2c, XIIC_IISR_OFFSET);
xiic_setreg32(i2c, XIIC_IISR_OFFSET, isr & mask);
}
static inline void xiic_irq_clr_en(struct xiic_i2c *i2c, u32 mask)
{
xiic_irq_clr(i2c, mask);
xiic_irq_en(i2c, mask);
}
static int xiic_clear_rx_fifo(struct xiic_i2c *i2c)
{
u8 sr;
unsigned long timeout;
timeout = jiffies + XIIC_I2C_TIMEOUT;
for (sr = xiic_getreg8(i2c, XIIC_SR_REG_OFFSET);
!(sr & XIIC_SR_RX_FIFO_EMPTY_MASK);
sr = xiic_getreg8(i2c, XIIC_SR_REG_OFFSET)) {
xiic_getreg8(i2c, XIIC_DRR_REG_OFFSET);
if (time_after(jiffies, timeout)) {
dev_err(i2c->dev, "Failed to clear rx fifo\n");
return -ETIMEDOUT;
}
}
return 0;
}
static int xiic_reinit(struct xiic_i2c *i2c)
{
int ret;
xiic_setreg32(i2c, XIIC_RESETR_OFFSET, XIIC_RESET_MASK);
/* Set receive Fifo depth to maximum (zero based). */
xiic_setreg8(i2c, XIIC_RFD_REG_OFFSET, IIC_RX_FIFO_DEPTH - 1);
/* Reset Tx Fifo. */
xiic_setreg8(i2c, XIIC_CR_REG_OFFSET, XIIC_CR_TX_FIFO_RESET_MASK);
/* Enable IIC Device, remove Tx Fifo reset & disable general call. */
xiic_setreg8(i2c, XIIC_CR_REG_OFFSET, XIIC_CR_ENABLE_DEVICE_MASK);
/* make sure RX fifo is empty */
ret = xiic_clear_rx_fifo(i2c);
if (ret)
return ret;
/* Enable interrupts */
xiic_setreg32(i2c, XIIC_DGIER_OFFSET, XIIC_GINTR_ENABLE_MASK);
xiic_irq_clr_en(i2c, XIIC_INTR_ARB_LOST_MASK);
return 0;
}
static void xiic_deinit(struct xiic_i2c *i2c)
{
u8 cr;
xiic_setreg32(i2c, XIIC_RESETR_OFFSET, XIIC_RESET_MASK);
/* Disable IIC Device. */
cr = xiic_getreg8(i2c, XIIC_CR_REG_OFFSET);
xiic_setreg8(i2c, XIIC_CR_REG_OFFSET, cr & ~XIIC_CR_ENABLE_DEVICE_MASK);
}
static void xiic_read_rx(struct xiic_i2c *i2c)
{
u8 bytes_in_fifo;
int i;
bytes_in_fifo = xiic_getreg8(i2c, XIIC_RFO_REG_OFFSET) + 1;
dev_dbg(i2c->adap.dev.parent,
"%s entry, bytes in fifo: %d, msg: %d, SR: 0x%x, CR: 0x%x\n",
__func__, bytes_in_fifo, xiic_rx_space(i2c),
xiic_getreg8(i2c, XIIC_SR_REG_OFFSET),
xiic_getreg8(i2c, XIIC_CR_REG_OFFSET));
if (bytes_in_fifo > xiic_rx_space(i2c))
bytes_in_fifo = xiic_rx_space(i2c);
for (i = 0; i < bytes_in_fifo; i++)
i2c->rx_msg->buf[i2c->rx_pos++] =
xiic_getreg8(i2c, XIIC_DRR_REG_OFFSET);
xiic_setreg8(i2c, XIIC_RFD_REG_OFFSET,
(xiic_rx_space(i2c) > IIC_RX_FIFO_DEPTH) ?
IIC_RX_FIFO_DEPTH - 1 : xiic_rx_space(i2c) - 1);
}
static int xiic_tx_fifo_space(struct xiic_i2c *i2c)
{
/* return the actual space left in the FIFO */
return IIC_TX_FIFO_DEPTH - xiic_getreg8(i2c, XIIC_TFO_REG_OFFSET) - 1;
}
static void xiic_fill_tx_fifo(struct xiic_i2c *i2c)
{
u8 fifo_space = xiic_tx_fifo_space(i2c);
int len = xiic_tx_space(i2c);
len = (len > fifo_space) ? fifo_space : len;
dev_dbg(i2c->adap.dev.parent, "%s entry, len: %d, fifo space: %d\n",
__func__, len, fifo_space);
while (len--) {
u16 data = i2c->tx_msg->buf[i2c->tx_pos++];
if ((xiic_tx_space(i2c) == 0) && (i2c->nmsgs == 1)) {
/* last message in transfer -> STOP */
data |= XIIC_TX_DYN_STOP_MASK;
dev_dbg(i2c->adap.dev.parent, "%s TX STOP\n", __func__);
}
xiic_setreg16(i2c, XIIC_DTR_REG_OFFSET, data);
}
}
static void xiic_wakeup(struct xiic_i2c *i2c, int code)
{
i2c->tx_msg = NULL;
i2c->rx_msg = NULL;
i2c->nmsgs = 0;
i2c->state = code;
wake_up(&i2c->wait);
}
static irqreturn_t xiic_process(int irq, void *dev_id)
{
struct xiic_i2c *i2c = dev_id;
u32 pend, isr, ier;
u32 clr = 0;
/* Get the interrupt Status from the IPIF. There is no clearing of
* interrupts in the IPIF. Interrupts must be cleared at the source.
* To find which interrupts are pending; AND interrupts pending with
* interrupts masked.
*/
mutex_lock(&i2c->lock);
isr = xiic_getreg32(i2c, XIIC_IISR_OFFSET);
ier = xiic_getreg32(i2c, XIIC_IIER_OFFSET);
pend = isr & ier;
dev_dbg(i2c->adap.dev.parent, "%s: IER: 0x%x, ISR: 0x%x, pend: 0x%x\n",
__func__, ier, isr, pend);
dev_dbg(i2c->adap.dev.parent, "%s: SR: 0x%x, msg: %p, nmsgs: %d\n",
__func__, xiic_getreg8(i2c, XIIC_SR_REG_OFFSET),
i2c->tx_msg, i2c->nmsgs);
/* Service requesting interrupt */
if ((pend & XIIC_INTR_ARB_LOST_MASK) ||
((pend & XIIC_INTR_TX_ERROR_MASK) &&
!(pend & XIIC_INTR_RX_FULL_MASK))) {
/* bus arbritration lost, or...
* Transmit error _OR_ RX completed
* if this happens when RX_FULL is not set
* this is probably a TX error
*/
dev_dbg(i2c->adap.dev.parent, "%s error\n", __func__);
/* dynamic mode seem to suffer from problems if we just flushes
* fifos and the next message is a TX with len 0 (only addr)
* reset the IP instead of just flush fifos
*/
xiic_reinit(i2c);
if (i2c->rx_msg)
xiic_wakeup(i2c, STATE_ERROR);
if (i2c->tx_msg)
xiic_wakeup(i2c, STATE_ERROR);
}
if (pend & XIIC_INTR_RX_FULL_MASK) {
/* Receive register/FIFO is full */
clr |= XIIC_INTR_RX_FULL_MASK;
if (!i2c->rx_msg) {
dev_dbg(i2c->adap.dev.parent,
"%s unexpected RX IRQ\n", __func__);
xiic_clear_rx_fifo(i2c);
goto out;
}
xiic_read_rx(i2c);
if (xiic_rx_space(i2c) == 0) {
/* this is the last part of the message */
i2c->rx_msg = NULL;
/* also clear TX error if there (RX complete) */
clr |= (isr & XIIC_INTR_TX_ERROR_MASK);
dev_dbg(i2c->adap.dev.parent,
"%s end of message, nmsgs: %d\n",
__func__, i2c->nmsgs);
/* send next message if this wasn't the last,
* otherwise the transfer will be finialise when
* receiving the bus not busy interrupt
*/
if (i2c->nmsgs > 1) {
i2c->nmsgs--;
i2c->tx_msg++;
dev_dbg(i2c->adap.dev.parent,
"%s will start next...\n", __func__);
__xiic_start_xfer(i2c);
}
}
}
if (pend & XIIC_INTR_BNB_MASK) {
/* IIC bus has transitioned to not busy */
clr |= XIIC_INTR_BNB_MASK;
/* The bus is not busy, disable BusNotBusy interrupt */
xiic_irq_dis(i2c, XIIC_INTR_BNB_MASK);
if (!i2c->tx_msg)
goto out;
if ((i2c->nmsgs == 1) && !i2c->rx_msg &&
xiic_tx_space(i2c) == 0)
xiic_wakeup(i2c, STATE_DONE);
else
xiic_wakeup(i2c, STATE_ERROR);
}
if (pend & (XIIC_INTR_TX_EMPTY_MASK | XIIC_INTR_TX_HALF_MASK)) {
/* Transmit register/FIFO is empty or ½ empty */
clr |= (pend &
(XIIC_INTR_TX_EMPTY_MASK | XIIC_INTR_TX_HALF_MASK));
if (!i2c->tx_msg) {
dev_dbg(i2c->adap.dev.parent,
"%s unexpected TX IRQ\n", __func__);
goto out;
}
xiic_fill_tx_fifo(i2c);
/* current message sent and there is space in the fifo */
if (!xiic_tx_space(i2c) && xiic_tx_fifo_space(i2c) >= 2) {
dev_dbg(i2c->adap.dev.parent,
"%s end of message sent, nmsgs: %d\n",
__func__, i2c->nmsgs);
if (i2c->nmsgs > 1) {
i2c->nmsgs--;
i2c->tx_msg++;
__xiic_start_xfer(i2c);
} else {
xiic_irq_dis(i2c, XIIC_INTR_TX_HALF_MASK);
dev_dbg(i2c->adap.dev.parent,
"%s Got TX IRQ but no more to do...\n",
__func__);
}
} else if (!xiic_tx_space(i2c) && (i2c->nmsgs == 1))
/* current frame is sent and is last,
* make sure to disable tx half
*/
xiic_irq_dis(i2c, XIIC_INTR_TX_HALF_MASK);
}
out:
dev_dbg(i2c->adap.dev.parent, "%s clr: 0x%x\n", __func__, clr);
xiic_setreg32(i2c, XIIC_IISR_OFFSET, clr);
mutex_unlock(&i2c->lock);
return IRQ_HANDLED;
}
static int xiic_bus_busy(struct xiic_i2c *i2c)
{
u8 sr = xiic_getreg8(i2c, XIIC_SR_REG_OFFSET);
return (sr & XIIC_SR_BUS_BUSY_MASK) ? -EBUSY : 0;
}
static int xiic_busy(struct xiic_i2c *i2c)
{
int tries = 3;
int err;
if (i2c->tx_msg)
return -EBUSY;
/* In single master mode bus can only be busy, when in use by this
* driver. If the register indicates bus being busy for some reason we
* should ignore it, since bus will never be released and i2c will be
* stuck forever.
*/
if (i2c->singlemaster) {
return 0;
}
/* for instance if previous transfer was terminated due to TX error
* it might be that the bus is on it's way to become available
* give it at most 3 ms to wake
*/
err = xiic_bus_busy(i2c);
while (err && tries--) {
msleep(1);
err = xiic_bus_busy(i2c);
}
return err;
}
static void xiic_start_recv(struct xiic_i2c *i2c)
{
u8 rx_watermark;
struct i2c_msg *msg = i2c->rx_msg = i2c->tx_msg;
unsigned long flags;
/* Clear and enable Rx full interrupt. */
xiic_irq_clr_en(i2c, XIIC_INTR_RX_FULL_MASK | XIIC_INTR_TX_ERROR_MASK);
/* we want to get all but last byte, because the TX_ERROR IRQ is used
* to inidicate error ACK on the address, and negative ack on the last
* received byte, so to not mix them receive all but last.
* In the case where there is only one byte to receive
* we can check if ERROR and RX full is set at the same time
*/
rx_watermark = msg->len;
if (rx_watermark > IIC_RX_FIFO_DEPTH)
rx_watermark = IIC_RX_FIFO_DEPTH;
xiic_setreg8(i2c, XIIC_RFD_REG_OFFSET, rx_watermark - 1);
local_irq_save(flags);
if (!(msg->flags & I2C_M_NOSTART))
/* write the address */
xiic_setreg16(i2c, XIIC_DTR_REG_OFFSET,
i2c_8bit_addr_from_msg(msg) | XIIC_TX_DYN_START_MASK);
xiic_irq_clr_en(i2c, XIIC_INTR_BNB_MASK);
xiic_setreg16(i2c, XIIC_DTR_REG_OFFSET,
msg->len | ((i2c->nmsgs == 1) ? XIIC_TX_DYN_STOP_MASK : 0));
local_irq_restore(flags);
if (i2c->nmsgs == 1)
/* very last, enable bus not busy as well */
xiic_irq_clr_en(i2c, XIIC_INTR_BNB_MASK);
/* the message is tx:ed */
i2c->tx_pos = msg->len;
}
static void xiic_start_send(struct xiic_i2c *i2c)
{
struct i2c_msg *msg = i2c->tx_msg;
xiic_irq_clr(i2c, XIIC_INTR_TX_ERROR_MASK);
dev_dbg(i2c->adap.dev.parent, "%s entry, msg: %p, len: %d",
__func__, msg, msg->len);
dev_dbg(i2c->adap.dev.parent, "%s entry, ISR: 0x%x, CR: 0x%x\n",
__func__, xiic_getreg32(i2c, XIIC_IISR_OFFSET),
xiic_getreg8(i2c, XIIC_CR_REG_OFFSET));
if (!(msg->flags & I2C_M_NOSTART)) {
/* write the address */
u16 data = i2c_8bit_addr_from_msg(msg) |
XIIC_TX_DYN_START_MASK;
if ((i2c->nmsgs == 1) && msg->len == 0)
/* no data and last message -> add STOP */
data |= XIIC_TX_DYN_STOP_MASK;
xiic_setreg16(i2c, XIIC_DTR_REG_OFFSET, data);
}
xiic_fill_tx_fifo(i2c);
/* Clear any pending Tx empty, Tx Error and then enable them. */
xiic_irq_clr_en(i2c, XIIC_INTR_TX_EMPTY_MASK | XIIC_INTR_TX_ERROR_MASK |
XIIC_INTR_BNB_MASK);
}
static irqreturn_t xiic_isr(int irq, void *dev_id)
{
struct xiic_i2c *i2c = dev_id;
u32 pend, isr, ier;
irqreturn_t ret = IRQ_NONE;
/* Do not processes a devices interrupts if the device has no
* interrupts pending
*/
dev_dbg(i2c->adap.dev.parent, "%s entry\n", __func__);
isr = xiic_getreg32(i2c, XIIC_IISR_OFFSET);
ier = xiic_getreg32(i2c, XIIC_IIER_OFFSET);
pend = isr & ier;
if (pend)
ret = IRQ_WAKE_THREAD;
return ret;
}
static void __xiic_start_xfer(struct xiic_i2c *i2c)
{
int first = 1;
int fifo_space = xiic_tx_fifo_space(i2c);
dev_dbg(i2c->adap.dev.parent, "%s entry, msg: %p, fifos space: %d\n",
__func__, i2c->tx_msg, fifo_space);
if (!i2c->tx_msg)
return;
i2c->rx_pos = 0;
i2c->tx_pos = 0;
i2c->state = STATE_START;
while ((fifo_space >= 2) && (first || (i2c->nmsgs > 1))) {
if (!first) {
i2c->nmsgs--;
i2c->tx_msg++;
i2c->tx_pos = 0;
} else
first = 0;
if (i2c->tx_msg->flags & I2C_M_RD) {
/* we dont date putting several reads in the FIFO */
xiic_start_recv(i2c);
return;
} else {
xiic_start_send(i2c);
if (xiic_tx_space(i2c) != 0) {
/* the message could not be completely sent */
break;
}
}
fifo_space = xiic_tx_fifo_space(i2c);
}
/* there are more messages or the current one could not be completely
* put into the FIFO, also enable the half empty interrupt
*/
if (i2c->nmsgs > 1 || xiic_tx_space(i2c))
xiic_irq_clr_en(i2c, XIIC_INTR_TX_HALF_MASK);
}
static int xiic_start_xfer(struct xiic_i2c *i2c)
{
int ret;
mutex_lock(&i2c->lock);
ret = xiic_reinit(i2c);
if (!ret)
__xiic_start_xfer(i2c);
mutex_unlock(&i2c->lock);
return ret;
}
static int xiic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
{
struct xiic_i2c *i2c = i2c_get_adapdata(adap);
int err;
dev_dbg(adap->dev.parent, "%s entry SR: 0x%x\n", __func__,
xiic_getreg8(i2c, XIIC_SR_REG_OFFSET));
err = pm_runtime_get_sync(i2c->dev);
if (err < 0)
return err;
err = xiic_busy(i2c);
if (err)
goto out;
i2c->tx_msg = msgs;
i2c->nmsgs = num;
err = xiic_start_xfer(i2c);
if (err < 0) {
dev_err(adap->dev.parent, "Error xiic_start_xfer\n");
goto out;
}
if (wait_event_timeout(i2c->wait, (i2c->state == STATE_ERROR) ||
(i2c->state == STATE_DONE), HZ)) {
err = (i2c->state == STATE_DONE) ? num : -EIO;
goto out;
} else {
i2c->tx_msg = NULL;
i2c->rx_msg = NULL;
i2c->nmsgs = 0;
err = -ETIMEDOUT;
goto out;
}
out:
pm_runtime_mark_last_busy(i2c->dev);
pm_runtime_put_autosuspend(i2c->dev);
return err;
}
static u32 xiic_func(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}
static const struct i2c_algorithm xiic_algorithm = {
.master_xfer = xiic_xfer,
.functionality = xiic_func,
};
static const struct i2c_adapter_quirks xiic_quirks = {
.max_read_len = 255,
};
static const struct i2c_adapter xiic_adapter = {
.owner = THIS_MODULE,
.name = DRIVER_NAME,
.class = I2C_CLASS_DEPRECATED,
.algo = &xiic_algorithm,
.quirks = &xiic_quirks,
};
static int xiic_i2c_probe(struct platform_device *pdev)
{
struct xiic_i2c *i2c;
struct xiic_i2c_platform_data *pdata;
struct resource *res;
int ret, irq;
u8 i;
u32 sr;
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);
irq = platform_get_irq(pdev, 0);
if (irq < 0)
return irq;
pdata = dev_get_platdata(&pdev->dev);
/* hook up driver to tree */
platform_set_drvdata(pdev, i2c);
i2c->adap = xiic_adapter;
i2c_set_adapdata(&i2c->adap, i2c);
i2c->adap.dev.parent = &pdev->dev;
i2c->adap.dev.of_node = pdev->dev.of_node;
mutex_init(&i2c->lock);
init_waitqueue_head(&i2c->wait);
i2c->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(i2c->clk)) {
if (PTR_ERR(i2c->clk) != -EPROBE_DEFER)
dev_err(&pdev->dev, "input clock not found.\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;
}
i2c->dev = &pdev->dev;
pm_runtime_set_autosuspend_delay(i2c->dev, XIIC_PM_TIMEOUT);
pm_runtime_use_autosuspend(i2c->dev);
pm_runtime_set_active(i2c->dev);
pm_runtime_enable(i2c->dev);
ret = devm_request_threaded_irq(&pdev->dev, irq, xiic_isr,
xiic_process, IRQF_ONESHOT,
pdev->name, i2c);
if (ret < 0) {
dev_err(&pdev->dev, "Cannot claim IRQ\n");
goto err_clk_dis;
}
i2c->singlemaster =
of_property_read_bool(pdev->dev.of_node, "single-master");
/*
* Detect endianness
* Try to reset the TX FIFO. Then check the EMPTY flag. If it is not
* set, assume that the endianness was wrong and swap.
*/
i2c->endianness = LITTLE;
xiic_setreg32(i2c, XIIC_CR_REG_OFFSET, XIIC_CR_TX_FIFO_RESET_MASK);
/* Reset is cleared in xiic_reinit */
sr = xiic_getreg32(i2c, XIIC_SR_REG_OFFSET);
if (!(sr & XIIC_SR_TX_FIFO_EMPTY_MASK))
i2c->endianness = BIG;
ret = xiic_reinit(i2c);
if (ret < 0) {
dev_err(&pdev->dev, "Cannot xiic_reinit\n");
goto err_clk_dis;
}
/* add i2c adapter to i2c tree */
ret = i2c_add_adapter(&i2c->adap);
if (ret) {
xiic_deinit(i2c);
goto err_clk_dis;
}
if (pdata) {
/* add in known devices to the bus */
for (i = 0; i < pdata->num_devices; i++)
i2c_new_client_device(&i2c->adap, pdata->devices + i);
}
return 0;
err_clk_dis:
pm_runtime_set_suspended(&pdev->dev);
pm_runtime_disable(&pdev->dev);
clk_disable_unprepare(i2c->clk);
return ret;
}
static int xiic_i2c_remove(struct platform_device *pdev)
{
struct xiic_i2c *i2c = platform_get_drvdata(pdev);
int ret;
/* remove adapter & data */
i2c_del_adapter(&i2c->adap);
ret = pm_runtime_get_sync(i2c->dev);
if (ret < 0)
return ret;
xiic_deinit(i2c);
pm_runtime_put_sync(i2c->dev);
clk_disable_unprepare(i2c->clk);
pm_runtime_disable(&pdev->dev);
pm_runtime_set_suspended(&pdev->dev);
pm_runtime_dont_use_autosuspend(&pdev->dev);
return 0;
}
#if defined(CONFIG_OF)
static const struct of_device_id xiic_of_match[] = {
{ .compatible = "xlnx,xps-iic-2.00.a", },
{},
};
MODULE_DEVICE_TABLE(of, xiic_of_match);
#endif
static int __maybe_unused xiic_i2c_runtime_suspend(struct device *dev)
{
struct xiic_i2c *i2c = dev_get_drvdata(dev);
clk_disable(i2c->clk);
return 0;
}
static int __maybe_unused xiic_i2c_runtime_resume(struct device *dev)
{
struct xiic_i2c *i2c = dev_get_drvdata(dev);
int ret;
ret = clk_enable(i2c->clk);
if (ret) {
dev_err(dev, "Cannot enable clock.\n");
return ret;
}
return 0;
}
static const struct dev_pm_ops xiic_dev_pm_ops = {
SET_RUNTIME_PM_OPS(xiic_i2c_runtime_suspend,
xiic_i2c_runtime_resume, NULL)
};
static struct platform_driver xiic_i2c_driver = {
.probe = xiic_i2c_probe,
.remove = xiic_i2c_remove,
.driver = {
.name = DRIVER_NAME,
.of_match_table = of_match_ptr(xiic_of_match),
.pm = &xiic_dev_pm_ops,
},
};
module_platform_driver(xiic_i2c_driver);
MODULE_AUTHOR("info@mocean-labs.com");
MODULE_DESCRIPTION("Xilinx I2C bus driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:"DRIVER_NAME);
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