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i2c: i2c-cdns: Implement workaround for hold quirk of the rev 1.0

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Revision 1.0 of this IP has a quirk where if during a long read transfer
the transfer_size register will go to 0, the master will send a NACK to
the slave prematurely.
The way to work around this is to reprogram the transfer_size register
mid-transfer when the only the receive fifo is known full, i.e. the I2C
bus is known non-active.
The workaround is based on the implementation in the linux-kernel.

Signed-off-by: Moritz Fischer <moritz.fischer@ettus.com>
Cc: Heiko Schocher <hs@denx.de>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: u-boot@lists.denx.de
This commit is contained in:
Moritz Fischer 2017-01-16 09:50:46 -08:00 • committed by Heiko Schocher
parent 0ec0c58643
commit 08c11aaefb
1 changed files with 89 additions and 30 deletions
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119
drivers/i2c/i2c-cdns.c
View file

@ -17,6 +17,7 @@
#include <i2c.h>
#include <fdtdec.h>
#include <mapmem.h>
#include <wait_bit.h>
DECLARE_GLOBAL_DATA_PTR;
@ -67,6 +68,8 @@ struct cdns_i2c_regs {
#define CDNS_I2C_FIFO_DEPTH 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)
#ifdef DEBUG
@ -247,15 +250,21 @@ 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;
/* 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);
/* Check message size against FIFO depth, and set hold bus bit
* if it is greater than FIFO depth
*/
if (len > CDNS_I2C_FIFO_DEPTH)
setbits_le32(&regs->control, CDNS_I2C_CONTROL_HOLD);
/* Clear the interrupts in status register */
writel(0xFF, &regs->interrupt_status);
writel(addr, &regs->address);
while (len--) {
@ -280,48 +289,98 @@ static int cdns_i2c_write_data(struct i2c_cdns_bus *i2c_bus, u32 addr, u8 *data,
return 0;
}
static int cdns_i2c_read_data(struct i2c_cdns_bus *i2c_bus, u32 addr, u8 *data,
u32 len)
static inline bool cdns_is_hold_quirk(int hold_quirk, int curr_recv_count)
{
u32 status;
u32 i = 0;
u8 *cur_data = data;
return hold_quirk && (curr_recv_count == CDNS_I2C_FIFO_DEPTH + 1);
}
/* TODO: Fix this */
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;
int curr_recv_count;
int updatetx, hold_quirk;
/* Check the hardware can handle the requested bytes */
if ((len < 0))
if ((recv_count < 0))
return -EINVAL;
curr_recv_count = recv_count;
/* Check for the message size against the FIFO depth */
if (recv_count > CDNS_I2C_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);
writel(len, &regs->transfer_size);
/* Wait for data */
do {
status = cdns_i2c_wait(regs, CDNS_I2C_INTERRUPT_COMP |
CDNS_I2C_INTERRUPT_DATA);
if (!status) {
/* Release the bus */
clrbits_le32(&regs->control, CDNS_I2C_CONTROL_HOLD);
return -ETIMEDOUT;
updatetx = recv_count > curr_recv_count;
hold_quirk = (i2c_bus->quirks & CDNS_I2C_BROKEN_HOLD_BIT) && updatetx;
while (recv_count) {
while (readl(&regs->status) & CDNS_I2C_STATUS_RXDV) {
if (recv_count < CDNS_I2C_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(hold_quirk, curr_recv_count))
break;
}
debug("Read %d bytes\n",
len - readl(&regs->transfer_size));
for (; i < len - readl(&regs->transfer_size); i++)
*(cur_data++) = readl(&regs->data);
} while (readl(&regs->transfer_size) != 0);
/* All done... release the bus */
if (!i2c_bus->hold_flag)
clrbits_le32(&regs->control, CDNS_I2C_CONTROL_HOLD);
#ifdef DEBUG
cdns_i2c_debug_status(regs);
#endif
if (cdns_is_hold_quirk(hold_quirk, curr_recv_count)) {
/* wait while fifo is full */
while (readl(&regs->transfer_size) !=
(curr_recv_count - CDNS_I2C_FIFO_DEPTH))
;
/*
* Check number of bytes to be received against maximum
* transfer size and update register accordingly.
*/
if ((recv_count - CDNS_I2C_FIFO_DEPTH) >
CDNS_I2C_TRANSFER_SIZE) {
writel(CDNS_I2C_TRANSFER_SIZE,
&regs->transfer_size);
curr_recv_count = CDNS_I2C_TRANSFER_SIZE +
CDNS_I2C_FIFO_DEPTH;
} else {
writel(recv_count - CDNS_I2C_FIFO_DEPTH,
&regs->transfer_size);
curr_recv_count = recv_count;
}
} else if (recv_count && !hold_quirk && !curr_recv_count) {
writel(addr, &regs->address);
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;
}
}
}
/* Wait for the address and data to be sent */
if (!cdns_i2c_wait(regs, CDNS_I2C_INTERRUPT_COMP))
return -ETIMEDOUT;
return 0;
}