[PATCH AUTOSEL 5.9 49/55] i2c: sh_mobile: implement atomic transfers

Sasha Levin
2020-11-10T04:04:21Z

From: Ulrich Hecht <uli+renesas@fpond.eu>

[ Upstream commit a49cc1fe9d64a2dc4e19b599204f403e5d25f44b ]

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>
---
drivers/i2c/busses/i2c-sh_mobile.c | 86 +++++++++++++++++++++++-------
1 file changed, 66 insertions(+), 20 deletions(-)

diff --git a/drivers/i2c/busses/i2c-sh_mobile.c b/drivers/i2c/busses/i2c-sh_mobile.c
index cab7255599991..bdd60770779ad 100644
--- a/drivers/i2c/busses/i2c-sh_mobile.c
+++ b/drivers/i2c/busses/i2c-sh_mobile.c
@@ -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;
@@ -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;
@@ -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 */
@@ -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);
@@ -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);
@@ -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);
@@ -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 = {
--
2.27.0