[PATCH 4.19 011/105] bus: sunxi-rsb: Support atomic transfers

Greg Kroah-Hartman
2022-12-05T19:18:08Z

From: Samuel Holland <samuel@sholland.org>

[ Upstream commit 077686da0e2162c4ea5ae0df205849c2a7a84479 ]

When communicating with a PMIC during system poweroff (pm_power_off()),
IRQs are disabled and we are in a RCU read-side critical section, so we
cannot use wait_for_completion_io_timeout(). Instead, poll the status
register for transfer completion.

Fixes: d787dcdb9c8f ("bus: sunxi-rsb: Add driver for Allwinner Reduced Serial Bus")
Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20221114015749.28490-3-samuel@sholland.org
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/bus/sunxi-rsb.c | 29 +++++++++++++++++++++--------
1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/drivers/bus/sunxi-rsb.c b/drivers/bus/sunxi-rsb.c
index b85d013a9185..d3fb350dc9ee 100644
--- a/drivers/bus/sunxi-rsb.c
+++ b/drivers/bus/sunxi-rsb.c
@@ -268,6 +268,9 @@ EXPORT_SYMBOL_GPL(sunxi_rsb_driver_register);
/* common code that starts a transfer */
static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
{
+ u32 int_mask, status;
+ bool timeout;
+
if (readl(rsb->regs + RSB_CTRL) & RSB_CTRL_START_TRANS) {
dev_dbg(rsb->dev, "RSB transfer still in progress\n");
return -EBUSY;
@@ -275,13 +278,23 @@ static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)

reinit_completion(&rsb->complete);

- writel(RSB_INTS_LOAD_BSY | RSB_INTS_TRANS_ERR | RSB_INTS_TRANS_OVER,
- rsb->regs + RSB_INTE);
+ int_mask = RSB_INTS_LOAD_BSY | RSB_INTS_TRANS_ERR | RSB_INTS_TRANS_OVER;
+ writel(int_mask, rsb->regs + RSB_INTE);
writel(RSB_CTRL_START_TRANS | RSB_CTRL_GLOBAL_INT_ENB,
rsb->regs + RSB_CTRL);

- if (!wait_for_completion_io_timeout(&rsb->complete,
- msecs_to_jiffies(100))) {
+ if (irqs_disabled()) {
+ timeout = readl_poll_timeout_atomic(rsb->regs + RSB_INTS,
+ status, (status & int_mask),
+ 10, 100000);
+ writel(status, rsb->regs + RSB_INTS);
+ } else {
+ timeout = !wait_for_completion_io_timeout(&rsb->complete,
+ msecs_to_jiffies(100));
+ status = rsb->status;
+ }
+
+ if (timeout) {
dev_dbg(rsb->dev, "RSB timeout\n");

/* abort the transfer */
@@ -293,18 +306,18 @@ static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
return -ETIMEDOUT;
}

- if (rsb->status & RSB_INTS_LOAD_BSY) {
+ if (status & RSB_INTS_LOAD_BSY) {
dev_dbg(rsb->dev, "RSB busy\n");
return -EBUSY;
}

- if (rsb->status & RSB_INTS_TRANS_ERR) {
- if (rsb->status & RSB_INTS_TRANS_ERR_ACK) {
+ if (status & RSB_INTS_TRANS_ERR) {
+ if (status & RSB_INTS_TRANS_ERR_ACK) {
dev_dbg(rsb->dev, "RSB slave nack\n");
return -EINVAL;
}

- if (rsb->status & RSB_INTS_TRANS_ERR_DATA) {
+ if (status & RSB_INTS_TRANS_ERR_DATA) {
dev_dbg(rsb->dev, "RSB transfer data error\n");
return -EIO;
}
--
2.35.1