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u-boot/drivers/i2c/i2c-cdns.c
Andrea Merello 419ddf944c I2C: cdns: Fix broken retry mechanism on arbitration lost. 
In the current implementation, in case of I2C arbitration lost, a retry is
attempted; the message counter and pointer are reset to the original values
and the I2C xfer process is restart from the beginning.

However the message counter and message pointer are respectively
decremented and incremented by one before attempting any transfer, causing
the 1st transfer not to be actually retried (in case of a single transfer,
nothing is actually retried at all).

This patch fixes this: in case of retry, the 1st transfer is also retried.

Tested on a ZynqMP Kria board, with upstream older u-boot, but the involved
file and underlying logic seem basically the same.

Signed-off-by: Andrea Merello <andrea.merello@iit.it>
2023-06-05 06:54:25 +02:00

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// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2015 Moritz Fischer <moritz.fischer@ettus.com>
* IP from Cadence (ID T-CS-PE-0007-100, Version R1p10f2)
*
* This file is based on: drivers/i2c/zynq_i2c.c,
* with added driver-model support and code cleanup.
*/
#include <common.h>
#include <dm.h>
#include <log.h>
#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/types.h>
#include <linux/io.h>
#include <linux/errno.h>
#include <dm/device_compat.h>
#include <dm/root.h>
#include <i2c.h>
#include <fdtdec.h>
#include <mapmem.h>
#include <wait_bit.h>
#include <clk.h>
/* i2c register set */
struct cdns_i2c_regs {
u32 control;
u32 status;
u32 address;
u32 data;
u32 interrupt_status;
u32 transfer_size;
u32 slave_mon_pause;
u32 time_out;
u32 interrupt_mask;
u32 interrupt_enable;
u32 interrupt_disable;
};
/* Control register fields */
#define CDNS_I2C_CONTROL_RW 0x00000001
#define CDNS_I2C_CONTROL_MS 0x00000002
#define CDNS_I2C_CONTROL_NEA 0x00000004
#define CDNS_I2C_CONTROL_ACKEN 0x00000008
#define CDNS_I2C_CONTROL_HOLD 0x00000010
#define CDNS_I2C_CONTROL_SLVMON 0x00000020
#define CDNS_I2C_CONTROL_CLR_FIFO 0x00000040
#define CDNS_I2C_CONTROL_DIV_B_SHIFT 8
#define CDNS_I2C_CONTROL_DIV_B_MASK 0x00003F00
#define CDNS_I2C_CONTROL_DIV_A_SHIFT 14
#define CDNS_I2C_CONTROL_DIV_A_MASK 0x0000C000
/* Status register values */
#define CDNS_I2C_STATUS_RXDV 0x00000020
#define CDNS_I2C_STATUS_TXDV 0x00000040
#define CDNS_I2C_STATUS_RXOVF 0x00000080
#define CDNS_I2C_STATUS_BA 0x00000100
/* Interrupt register fields */
#define CDNS_I2C_INTERRUPT_COMP 0x00000001
#define CDNS_I2C_INTERRUPT_DATA 0x00000002
#define CDNS_I2C_INTERRUPT_NACK 0x00000004
#define CDNS_I2C_INTERRUPT_TO 0x00000008
#define CDNS_I2C_INTERRUPT_SLVRDY 0x00000010
#define CDNS_I2C_INTERRUPT_RXOVF 0x00000020
#define CDNS_I2C_INTERRUPT_TXOVF 0x00000040
#define CDNS_I2C_INTERRUPT_RXUNF 0x00000080
#define CDNS_I2C_INTERRUPT_ARBLOST 0x00000200
#define CDNS_I2C_INTERRUPTS_MASK (CDNS_I2C_INTERRUPT_COMP | \
CDNS_I2C_INTERRUPT_DATA | \
CDNS_I2C_INTERRUPT_NACK | \
CDNS_I2C_INTERRUPT_TO | \
CDNS_I2C_INTERRUPT_SLVRDY | \
CDNS_I2C_INTERRUPT_RXOVF | \
CDNS_I2C_INTERRUPT_TXOVF | \
CDNS_I2C_INTERRUPT_RXUNF | \
CDNS_I2C_INTERRUPT_ARBLOST)
#define CDNS_I2C_FIFO_DEPTH_DEFAULT 16
#define CDNS_I2C_TRANSFER_SIZE_MAX 255 /* Controller transfer limit */
#define CDNS_I2C_TRANSFER_SIZE (CDNS_I2C_TRANSFER_SIZE_MAX - 3)
#define CDNS_I2C_BROKEN_HOLD_BIT BIT(0)
#define CDNS_I2C_ARB_LOST_MAX_RETRIES 10
#ifdef DEBUG
static void cdns_i2c_debug_status(struct cdns_i2c_regs *cdns_i2c)
{
int int_status;
int status;
int_status = readl(&cdns_i2c->interrupt_status);
status = readl(&cdns_i2c->status);
if (int_status || status) {
debug("Status: ");
if (int_status & CDNS_I2C_INTERRUPT_COMP)
debug("COMP ");
if (int_status & CDNS_I2C_INTERRUPT_DATA)
debug("DATA ");
if (int_status & CDNS_I2C_INTERRUPT_NACK)
debug("NACK ");
if (int_status & CDNS_I2C_INTERRUPT_TO)
debug("TO ");
if (int_status & CDNS_I2C_INTERRUPT_SLVRDY)
debug("SLVRDY ");
if (int_status & CDNS_I2C_INTERRUPT_RXOVF)
debug("RXOVF ");
if (int_status & CDNS_I2C_INTERRUPT_TXOVF)
debug("TXOVF ");
if (int_status & CDNS_I2C_INTERRUPT_RXUNF)
debug("RXUNF ");
if (int_status & CDNS_I2C_INTERRUPT_ARBLOST)
debug("ARBLOST ");
if (status & CDNS_I2C_STATUS_RXDV)
debug("RXDV ");
if (status & CDNS_I2C_STATUS_TXDV)
debug("TXDV ");
if (status & CDNS_I2C_STATUS_RXOVF)
debug("RXOVF ");
if (status & CDNS_I2C_STATUS_BA)
debug("BA ");
debug("TS%d ", readl(&cdns_i2c->transfer_size));
debug("\n");
}
}
#endif
struct i2c_cdns_bus {
int id;
unsigned int input_freq;
struct cdns_i2c_regs __iomem *regs; /* register base */
int hold_flag;
u32 quirks;
u32 fifo_depth;
};
struct cdns_i2c_platform_data {
u32 quirks;
};
/* Wait for an interrupt */
static u32 cdns_i2c_wait(struct cdns_i2c_regs *cdns_i2c, u32 mask)
{
int timeout, int_status;
for (timeout = 0; timeout < 100; timeout++) {
int_status = readl(&cdns_i2c->interrupt_status);
if (int_status & mask)
break;
udelay(100);
}
/* Clear interrupt status flags */
writel(int_status & mask, &cdns_i2c->interrupt_status);
return int_status & mask;
}
#define CDNS_I2C_DIVA_MAX 4
#define CDNS_I2C_DIVB_MAX 64
static int cdns_i2c_calc_divs(unsigned long *f, unsigned long input_clk,
unsigned int *a, unsigned int *b)
{
unsigned long fscl = *f, best_fscl = *f, actual_fscl, temp;
unsigned int div_a, div_b, calc_div_a = 0, calc_div_b = 0;
unsigned int last_error, current_error;
/* calculate (divisor_a+1) x (divisor_b+1) */
temp = input_clk / (22 * fscl);
/*
* If the calculated value is negative or 0CDNS_I2C_DIVA_MAX,
* the fscl input is out of range. Return error.
*/
if (!temp || (temp > (CDNS_I2C_DIVA_MAX * CDNS_I2C_DIVB_MAX)))
return -EINVAL;
last_error = -1;
for (div_a = 0; div_a < CDNS_I2C_DIVA_MAX; div_a++) {
div_b = DIV_ROUND_UP(input_clk, 22 * fscl * (div_a + 1));
if ((div_b < 1) || (div_b > CDNS_I2C_DIVB_MAX))
continue;
div_b--;
actual_fscl = input_clk / (22 * (div_a + 1) * (div_b + 1));
if (actual_fscl > fscl)
continue;
current_error = ((actual_fscl > fscl) ? (actual_fscl - fscl) :
(fscl - actual_fscl));
if (last_error > current_error) {
calc_div_a = div_a;
calc_div_b = div_b;
best_fscl = actual_fscl;
last_error = current_error;
}
}
*a = calc_div_a;
*b = calc_div_b;
*f = best_fscl;
return 0;
}
static int cdns_i2c_set_bus_speed(struct udevice *dev, unsigned int speed)
{
struct i2c_cdns_bus *bus = dev_get_priv(dev);
u32 div_a = 0, div_b = 0;
unsigned long speed_p = speed;
int ret = 0;
if (speed > I2C_SPEED_FAST_RATE) {
debug("%s, failed to set clock speed to %u\n", __func__,
speed);
return -EINVAL;
}
ret = cdns_i2c_calc_divs(&speed_p, bus->input_freq, &div_a, &div_b);
if (ret)
return ret;
debug("%s: div_a: %d, div_b: %d, input freq: %d, speed: %d/%ld\n",
__func__, div_a, div_b, bus->input_freq, speed, speed_p);
writel((div_b << CDNS_I2C_CONTROL_DIV_B_SHIFT) |
(div_a << CDNS_I2C_CONTROL_DIV_A_SHIFT), &bus->regs->control);
/* Enable master mode, ack, and 7-bit addressing */
setbits_le32(&bus->regs->control, CDNS_I2C_CONTROL_MS |
CDNS_I2C_CONTROL_ACKEN | CDNS_I2C_CONTROL_NEA);
return 0;
}
static inline u32 is_arbitration_lost(struct cdns_i2c_regs *regs)
{
return (readl(&regs->interrupt_status) & CDNS_I2C_INTERRUPT_ARBLOST);
}
static int cdns_i2c_write_data(struct i2c_cdns_bus *i2c_bus, u32 addr, u8 *data,
u32 len)
{
u8 *cur_data = data;
struct cdns_i2c_regs *regs = i2c_bus->regs;
u32 ret;
bool start = 1;
/* Set the controller in Master transmit mode and clear FIFO */
setbits_le32(&regs->control, CDNS_I2C_CONTROL_CLR_FIFO);
clrbits_le32(&regs->control, CDNS_I2C_CONTROL_RW);
/*
* For sequential data load hold the bus.
*/
if (len > 1)
setbits_le32(&regs->control, CDNS_I2C_CONTROL_HOLD);
/* Clear the interrupts in status register */
writel(CDNS_I2C_INTERRUPTS_MASK, &regs->interrupt_status);
/* In case of Probe (i.e no data), start the transfer */
if (!len)
writel(addr, &regs->address);
while (len-- && !is_arbitration_lost(regs)) {
writel(*(cur_data++), &regs->data);
/* Trigger write only after loading data */
if (start) {
writel(addr, &regs->address);
start = 0;
}
if (len && readl(&regs->transfer_size) == i2c_bus->fifo_depth) {
ret = cdns_i2c_wait(regs, CDNS_I2C_INTERRUPT_COMP |
CDNS_I2C_INTERRUPT_ARBLOST);
if (ret & CDNS_I2C_INTERRUPT_ARBLOST)
return -EAGAIN;
if (ret & CDNS_I2C_INTERRUPT_COMP)
continue;
/* Release the bus */
clrbits_le32(&regs->control,
CDNS_I2C_CONTROL_HOLD);
return -ETIMEDOUT;
}
}
if (len && is_arbitration_lost(regs))
return -EAGAIN;
/* All done... release the bus */
if (!i2c_bus->hold_flag)
clrbits_le32(&regs->control, CDNS_I2C_CONTROL_HOLD);
/* Wait for the address and data to be sent */
ret = cdns_i2c_wait(regs, CDNS_I2C_INTERRUPT_COMP |
CDNS_I2C_INTERRUPT_ARBLOST);
if (!(ret & (CDNS_I2C_INTERRUPT_ARBLOST |
CDNS_I2C_INTERRUPT_COMP)))
return -ETIMEDOUT;
if (ret & CDNS_I2C_INTERRUPT_ARBLOST)
return -EAGAIN;
return 0;
}
static inline bool cdns_is_hold_quirk(struct i2c_cdns_bus *i2c_bus, int hold_quirk,
int curr_recv_count)
{
return hold_quirk && (curr_recv_count == i2c_bus->fifo_depth + 1);
}
static int cdns_i2c_read_data(struct i2c_cdns_bus *i2c_bus, u32 addr, u8 *data,
u32 recv_count)
{
u8 *cur_data = data;
struct cdns_i2c_regs *regs = i2c_bus->regs;
u32 curr_recv_count;
int updatetx, hold_quirk;
u32 ret;
curr_recv_count = recv_count;
/* Check for the message size against the FIFO depth */
if (recv_count > i2c_bus->fifo_depth)
setbits_le32(&regs->control, CDNS_I2C_CONTROL_HOLD);
setbits_le32(&regs->control, CDNS_I2C_CONTROL_CLR_FIFO |
CDNS_I2C_CONTROL_RW);
if (recv_count > CDNS_I2C_TRANSFER_SIZE) {
curr_recv_count = CDNS_I2C_TRANSFER_SIZE;
writel(curr_recv_count, &regs->transfer_size);
} else {
writel(recv_count, &regs->transfer_size);
}
/* Start reading data */
writel(addr, &regs->address);
updatetx = recv_count > curr_recv_count;
hold_quirk = (i2c_bus->quirks & CDNS_I2C_BROKEN_HOLD_BIT) && updatetx;
while (recv_count && !is_arbitration_lost(regs)) {
while (readl(&regs->status) & CDNS_I2C_STATUS_RXDV) {
if (recv_count < i2c_bus->fifo_depth &&
!i2c_bus->hold_flag) {
clrbits_le32(&regs->control,
CDNS_I2C_CONTROL_HOLD);
}
*(cur_data)++ = readl(&regs->data);
recv_count--;
curr_recv_count--;
if (cdns_is_hold_quirk(i2c_bus, hold_quirk, curr_recv_count))
break;
}
if (cdns_is_hold_quirk(i2c_bus, hold_quirk, curr_recv_count)) {
/* wait while fifo is full */
while (readl(&regs->transfer_size) !=
(curr_recv_count - i2c_bus->fifo_depth))
;
/*
* Check number of bytes to be received against maximum
* transfer size and update register accordingly.
*/
if ((recv_count - i2c_bus->fifo_depth) >
CDNS_I2C_TRANSFER_SIZE) {
writel(CDNS_I2C_TRANSFER_SIZE,
&regs->transfer_size);
curr_recv_count = CDNS_I2C_TRANSFER_SIZE +
i2c_bus->fifo_depth;
} else {
writel(recv_count - i2c_bus->fifo_depth,
&regs->transfer_size);
curr_recv_count = recv_count;
}
} else if (recv_count && !hold_quirk && !curr_recv_count) {
if (recv_count > CDNS_I2C_TRANSFER_SIZE) {
writel(CDNS_I2C_TRANSFER_SIZE,
&regs->transfer_size);
curr_recv_count = CDNS_I2C_TRANSFER_SIZE;
} else {
writel(recv_count, &regs->transfer_size);
curr_recv_count = recv_count;
}
writel(addr, &regs->address);
}
}
/* Wait for the address and data to be sent */
ret = cdns_i2c_wait(regs, CDNS_I2C_INTERRUPT_COMP |
CDNS_I2C_INTERRUPT_ARBLOST);
if (!(ret & (CDNS_I2C_INTERRUPT_ARBLOST |
CDNS_I2C_INTERRUPT_COMP)))
return -ETIMEDOUT;
if (ret & CDNS_I2C_INTERRUPT_ARBLOST)
return -EAGAIN;
return 0;
}
static int cdns_i2c_xfer(struct udevice *dev, struct i2c_msg *msg,
int nmsgs)
{
struct i2c_cdns_bus *i2c_bus = dev_get_priv(dev);
int ret = 0;
int count;
bool hold_quirk;
struct i2c_msg *message = msg;
int num_msgs = nmsgs;
hold_quirk = !!(i2c_bus->quirks & CDNS_I2C_BROKEN_HOLD_BIT);
if (nmsgs > 1) {
/*
* This controller does not give completion interrupt after a
* master receive message if HOLD bit is set (repeated start),
* resulting in SW timeout. Hence, if a receive message is
* followed by any other message, an error is returned
* indicating that this sequence is not supported.
*/
for (count = 0; (count < nmsgs - 1) && hold_quirk; count++) {
if (msg[count].flags & I2C_M_RD) {
printf("Can't do repeated start after a receive message\n");
return -EOPNOTSUPP;
}
}
i2c_bus->hold_flag = 1;
setbits_le32(&i2c_bus->regs->control, CDNS_I2C_CONTROL_HOLD);
} else {
i2c_bus->hold_flag = 0;
}
debug("i2c_xfer: %d messages\n", nmsgs);
for (u8 retry = 0; retry < CDNS_I2C_ARB_LOST_MAX_RETRIES &&
nmsgs > 0;) {
debug("i2c_xfer: chip=0x%x, len=0x%x\n", msg->addr, msg->len);
if (msg->flags & I2C_M_RD) {
ret = cdns_i2c_read_data(i2c_bus, msg->addr, msg->buf,
msg->len);
} else {
ret = cdns_i2c_write_data(i2c_bus, msg->addr, msg->buf,
msg->len);
}
if (ret == -EAGAIN) {
msg = message;
nmsgs = num_msgs;
retry++;
printf("%s,arbitration lost, retrying:%d\n", __func__,
retry);
continue;
}
nmsgs--;
msg++;
if (ret) {
debug("i2c_write: error sending\n");
return -EREMOTEIO;
}
}
return ret;
}
static int cdns_i2c_of_to_plat(struct udevice *dev)
{
struct i2c_cdns_bus *i2c_bus = dev_get_priv(dev);
struct cdns_i2c_platform_data *pdata =
(struct cdns_i2c_platform_data *)dev_get_driver_data(dev);
struct clk clk;
int ret;
i2c_bus->regs = dev_read_addr_ptr(dev);
if (!i2c_bus->regs)
return -EINVAL;
if (pdata)
i2c_bus->quirks = pdata->quirks;
ret = clk_get_by_index(dev, 0, &clk);
if (ret)
return ret;
i2c_bus->input_freq = clk_get_rate(&clk);
ret = clk_enable(&clk);
if (ret) {
dev_err(dev, "failed to enable clock\n");
return ret;
}
/* Update FIFO depth based on device tree entry */
i2c_bus->fifo_depth = dev_read_u32_default(dev, "fifo-depth",
CDNS_I2C_FIFO_DEPTH_DEFAULT);
return 0;
}
static const struct dm_i2c_ops cdns_i2c_ops = {
.xfer = cdns_i2c_xfer,
.set_bus_speed = cdns_i2c_set_bus_speed,
};
static const struct cdns_i2c_platform_data r1p10_i2c_def = {
.quirks = CDNS_I2C_BROKEN_HOLD_BIT,
};
static const struct udevice_id cdns_i2c_of_match[] = {
{ .compatible = "cdns,i2c-r1p10", .data = (ulong)&r1p10_i2c_def },
{ .compatible = "cdns,i2c-r1p14" },
{ /* end of table */ }
};
U_BOOT_DRIVER(cdns_i2c) = {
.name = "i2c_cdns",
.id = UCLASS_I2C,
.of_match = cdns_i2c_of_match,
.of_to_plat = cdns_i2c_of_to_plat,
.priv_auto = sizeof(struct i2c_cdns_bus),
.ops = &cdns_i2c_ops,
};
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