diff mbox series

[v6,3/3] i2c-ocores: sifive: add polling mode workaround for FU540-C000 SoC.

Message ID 1558445574-16471-4-git-send-email-sagar.kadam@sifive.com (mailing list archive)
State New, archived
Headers show
Series Extend dt bindings to support I2C on sifive devices and a fix broken IRQ in polling mode. | expand

Commit Message

Sagar Shrikant Kadam May 21, 2019, 1:32 p.m. UTC 
The i2c-ocore driver already has a polling mode interface.But it needs
a workaround for FU540 Chipset on HiFive unleashed board (RevA00).
There is an erratum in FU540 chip that prevents interrupt driven i2c
transfers from working, and also the I2C controller's interrupt bit
cannot be cleared if set, due to this the existing i2c polling mode
interface added in mainline earlier doesn't work, and CPU stall's
infinitely, when-ever i2c transfer is initiated.

Ref:
	commit dd7dbf0eb090 ("i2c: ocores: refactor setup for polling")

The workaround / fix under OCORES_FLAG_BROKEN_IRQ is particularly for
FU540-COOO SoC.

The polling function identifies a SiFive device based on the device node
and enables the workaround.

Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@sifive.com>
---
 drivers/i2c/busses/i2c-ocores.c | 38 +++++++++++++++++++++++++++++++++-----
 1 file changed, 33 insertions(+), 5 deletions(-)

Comments

Andrew Lunn May 21, 2019, 1:54 p.m. UTC | #1 
>  static void ocores_process_polling(struct ocores_i2c *i2c)
>  {
> +	const struct of_device_id *match;
> +
> +	match = of_match_node(ocores_i2c_match, i2c->adap.dev.of_node);
> +
>  	while (1) {
>  		irqreturn_t ret;
>  		int err;

Please keep with the idea of i2c->flags, which is set during probe.
Just because it was removed because it was no longer needed does not
stop you from putting it back again if it is needed.

       Andrew
Sagar Shrikant Kadam May 22, 2019, 4:58 a.m. UTC | #2 
Hi Andrew,

On Tue, May 21, 2019 at 7:24 PM Andrew Lunn <andrew@lunn.ch> wrote:
>
> >  static void ocores_process_polling(struct ocores_i2c *i2c)
> >  {
> > +     const struct of_device_id *match;
> > +
> > +     match = of_match_node(ocores_i2c_match, i2c->adap.dev.of_node);
> > +
> >       while (1) {
> >               irqreturn_t ret;
> >               int err;
>
> Please keep with the idea of i2c->flags, which is set during probe.
> Just because it was removed because it was no longer needed does not
> stop you from putting it back again if it is needed.
>
I had modified the implementation, so as to keep it compatible with
the new implementation of polling mode.
As per your suggestion, I will keep the older method (the v5 version
which you Reviewed earlier : https://lkml.org/lkml/2019/5/20/1261)
 and submit a v7 for this.

>        Andrew

Thanks & Regards,
Sagar
diff mbox series

Patch

diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c
index b334fa2..3175c72 100644
--- a/drivers/i2c/busses/i2c-ocores.c
+++ b/drivers/i2c/busses/i2c-ocores.c
@@ -84,6 +84,10 @@  struct ocores_i2c {
 #define TYPE_GRLIB		1
 #define TYPE_SIFIVE_REV0	2
 
+#define OCORES_FLAG_BROKEN_IRQ BIT(1) /* Broken IRQ for FU540-C000 SoC */
+
+static const struct of_device_id ocores_i2c_match[];
+
 static void oc_setreg_8(struct ocores_i2c *i2c, int reg, u8 value)
 {
 	iowrite8(value, i2c->base + (reg << i2c->reg_shift));
@@ -236,9 +240,13 @@  static irqreturn_t ocores_isr(int irq, void *dev_id)
 	struct ocores_i2c *i2c = dev_id;
 	u8 stat = oc_getreg(i2c, OCI2C_STATUS);
 
-	if (!(stat & OCI2C_STAT_IF))
+	if (irq == OCORES_FLAG_BROKEN_IRQ) {
+		if (stat & OCI2C_STAT_IF)
+			if (!(stat & OCI2C_STAT_BUSY))
+				return IRQ_NONE;
+	} else if (!(stat & OCI2C_STAT_IF)) {
 		return IRQ_NONE;
-
+	}
 	ocores_process(i2c, stat);
 
 	return IRQ_HANDLED;
@@ -340,6 +348,10 @@  static int ocores_poll_wait(struct ocores_i2c *i2c)
  */
 static void ocores_process_polling(struct ocores_i2c *i2c)
 {
+	const struct of_device_id *match;
+
+	match = of_match_node(ocores_i2c_match, i2c->adap.dev.of_node);
+
 	while (1) {
 		irqreturn_t ret;
 		int err;
@@ -350,9 +362,25 @@  static void ocores_process_polling(struct ocores_i2c *i2c)
 			break; /* timeout */
 		}
 
-		ret = ocores_isr(-1, i2c);
-		if (ret == IRQ_NONE)
-			break; /* all messages have been transferred */
+		/*
+		 * If it's a SiFive Device(FU540-C000 SoC ) use
+		 * OCORES_FLAG_BROKEN_IRQ to enable workaround in
+		 * polling mode.
+		 */
+		if (match && (long)match->data == TYPE_SIFIVE_REV0) {
+			ret = ocores_isr(OCORES_FLAG_BROKEN_IRQ, i2c);
+			if (ret == IRQ_NONE)
+				break; /* all messages have been transferred */
+			else
+				if (i2c->state == STATE_DONE)
+					break;
+		} else {
+			ret = ocores_isr(-1, i2c);
+			if (ret == IRQ_NONE)
+				break; /* all messages have been transferred */
+
+		}
+
 	}
 }