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i2c: sh_mobile: implement atomic transfers
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[ Upstream commit a49cc1f ]

Implements atomic transfers to fix reboot/shutdown on r8a7790 Lager and
similar boards.

Signed-off-by: Ulrich Hecht <uli+renesas@fpond.eu>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
[wsa: some whitespace fixing]
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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@gregkh
Ulrich Hecht authored and gregkh committed Nov 18, 2020
1 parent 1e00436 commit 168b746
Showing 1 changed file with 66 additions and 20 deletions.
86 changes: 66 additions & 20 deletions drivers/i2c/busses/i2c-sh_mobile.c
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Original file line number Diff line number Diff line change
Expand Up @@ -129,6 +129,7 @@ struct sh_mobile_i2c_data {
int sr;
bool send_stop;
bool stop_after_dma;
bool atomic_xfer;

struct resource *res;
struct dma_chan *dma_tx;
Expand Down Expand Up @@ -330,13 +331,15 @@ static unsigned char i2c_op(struct sh_mobile_i2c_data *pd, enum sh_mobile_i2c_op
ret = iic_rd(pd, ICDR);
break;
case OP_RX_STOP: /* enable DTE interrupt, issue stop */
iic_wr(pd, ICIC,
ICIC_DTEE | ICIC_WAITE | ICIC_ALE | ICIC_TACKE);
if (!pd->atomic_xfer)
iic_wr(pd, ICIC,
ICIC_DTEE | ICIC_WAITE | ICIC_ALE | ICIC_TACKE);
iic_wr(pd, ICCR, ICCR_ICE | ICCR_RACK);
break;
case OP_RX_STOP_DATA: /* enable DTE interrupt, read data, issue stop */
iic_wr(pd, ICIC,
ICIC_DTEE | ICIC_WAITE | ICIC_ALE | ICIC_TACKE);
if (!pd->atomic_xfer)
iic_wr(pd, ICIC,
ICIC_DTEE | ICIC_WAITE | ICIC_ALE | ICIC_TACKE);
ret = iic_rd(pd, ICDR);
iic_wr(pd, ICCR, ICCR_ICE | ICCR_RACK);
break;
Expand Down Expand Up @@ -429,7 +432,8 @@ static irqreturn_t sh_mobile_i2c_isr(int irq, void *dev_id)

if (wakeup) {
pd->sr |= SW_DONE;
wake_up(&pd->wait);
if (!pd->atomic_xfer)
wake_up(&pd->wait);
}

/* defeat write posting to avoid spurious WAIT interrupts */
Expand Down Expand Up @@ -581,6 +585,9 @@ static void start_ch(struct sh_mobile_i2c_data *pd, struct i2c_msg *usr_msg,
pd->pos = -1;
pd->sr = 0;

if (pd->atomic_xfer)
return;

pd->dma_buf = i2c_get_dma_safe_msg_buf(pd->msg, 8);
if (pd->dma_buf)
sh_mobile_i2c_xfer_dma(pd);
Expand Down Expand Up @@ -637,15 +644,13 @@ static int poll_busy(struct sh_mobile_i2c_data *pd)
return i ? 0 : -ETIMEDOUT;
}

static int sh_mobile_i2c_xfer(struct i2c_adapter *adapter,
struct i2c_msg *msgs,
int num)
static int sh_mobile_xfer(struct sh_mobile_i2c_data *pd,
struct i2c_msg *msgs, int num)
{
struct sh_mobile_i2c_data *pd = i2c_get_adapdata(adapter);
struct i2c_msg *msg;
int err = 0;
int i;
long timeout;
long time_left;

/* Wake up device and enable clock */
pm_runtime_get_sync(pd->dev);
Expand All @@ -662,15 +667,35 @@ static int sh_mobile_i2c_xfer(struct i2c_adapter *adapter,
if (do_start)
i2c_op(pd, OP_START);

/* The interrupt handler takes care of the rest... */
timeout = wait_event_timeout(pd->wait,
pd->sr & (ICSR_TACK | SW_DONE),
adapter->timeout);

/* 'stop_after_dma' tells if DMA transfer was complete */
i2c_put_dma_safe_msg_buf(pd->dma_buf, pd->msg, pd->stop_after_dma);
if (pd->atomic_xfer) {
unsigned long j = jiffies + pd->adap.timeout;

time_left = time_before_eq(jiffies, j);
while (time_left &&
!(pd->sr & (ICSR_TACK | SW_DONE))) {
unsigned char sr = iic_rd(pd, ICSR);

if (sr & (ICSR_AL | ICSR_TACK |
ICSR_WAIT | ICSR_DTE)) {
sh_mobile_i2c_isr(0, pd);
udelay(150);
} else {
cpu_relax();
}
time_left = time_before_eq(jiffies, j);
}
} else {
/* The interrupt handler takes care of the rest... */
time_left = wait_event_timeout(pd->wait,
pd->sr & (ICSR_TACK | SW_DONE),
pd->adap.timeout);

/* 'stop_after_dma' tells if DMA xfer was complete */
i2c_put_dma_safe_msg_buf(pd->dma_buf, pd->msg,
pd->stop_after_dma);
}

if (!timeout) {
if (!time_left) {
dev_err(pd->dev, "Transfer request timed out\n");
if (pd->dma_direction != DMA_NONE)
sh_mobile_i2c_cleanup_dma(pd);
Expand All @@ -696,14 +721,35 @@ static int sh_mobile_i2c_xfer(struct i2c_adapter *adapter,
return err ?: num;
}

static int sh_mobile_i2c_xfer(struct i2c_adapter *adapter,
struct i2c_msg *msgs,
int num)
{
struct sh_mobile_i2c_data *pd = i2c_get_adapdata(adapter);

pd->atomic_xfer = false;
return sh_mobile_xfer(pd, msgs, num);
}

static int sh_mobile_i2c_xfer_atomic(struct i2c_adapter *adapter,
struct i2c_msg *msgs,
int num)
{
struct sh_mobile_i2c_data *pd = i2c_get_adapdata(adapter);

pd->atomic_xfer = true;
return sh_mobile_xfer(pd, msgs, num);
}

static u32 sh_mobile_i2c_func(struct i2c_adapter *adapter)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
}

static const struct i2c_algorithm sh_mobile_i2c_algorithm = {
.functionality = sh_mobile_i2c_func,
.master_xfer = sh_mobile_i2c_xfer,
.functionality = sh_mobile_i2c_func,
.master_xfer = sh_mobile_i2c_xfer,
.master_xfer_atomic = sh_mobile_i2c_xfer_atomic,
};

static const struct i2c_adapter_quirks sh_mobile_i2c_quirks = {
Expand Down

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