The P2040/P2041 has an erratum where the normal i2c recovery mechanism
does not work. Implement the alternative recovery mechanism documented
in the P2040 Chip Errata Rev Q.
Signed-off-by: Chris Packham <chris.pack...@alliedtelesis.co.nz>
---
drivers/i2c/busses/i2c-mpc.c | 88 +++++++++++++++++++++++++++++++++++-
1 file changed, 86 insertions(+), 2 deletions(-)
diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
index 30d9e89a3db2..052e37718771 100644
--- a/drivers/i2c/busses/i2c-mpc.c
+++ b/drivers/i2c/busses/i2c-mpc.c
@@ -45,6 +45,7 @@
#define CCR_MTX 0x10
#define CCR_TXAK 0x08
#define CCR_RSTA 0x04
+#define CCR_RSVD 0x02
#define CSR_MCF 0x80
#define CSR_MAAS 0x40
@@ -97,7 +98,7 @@ struct mpc_i2c {
u32 block;
int rc;
int expect_rxack;
-
+ bool has_errata_A004447;
};
struct mpc_i2c_divider {
@@ -136,6 +137,83 @@ static void mpc_i2c_fixup(struct mpc_i2c *i2c)
}
}
+static int i2c_mpc_wait_sr(struct mpc_i2c *i2c, int mask)
+{
+ unsigned long timeout = jiffies + usecs_to_jiffies(100);
+ int ret = 0;
+
+ while ((readb(i2c->base + MPC_I2C_SR) & mask) == 0) {
+ if (time_after(jiffies, timeout)) {
+ ret = -ETIMEDOUT;
+ break;
+ }
+ cond_resched();
+ }
+
+ return ret;
+}
+
+/*
+ * Workaround for Erratum A004447. From the P2040CE Rev Q
+ *
+ * 1. Set up the frequency divider and sampling rate.
+ * 2. I2CCR - a0h
+ * 3. Poll for I2CSR[MBB] to get set.
+ * 4. If I2CSR[MAL] is set (an indication that SDA is stuck low), then go to
+ * step 5. If MAL is not set, then go to step 13.
+ * 5. I2CCR - 00h
+ * 6. I2CCR - 22h
+ * 7. I2CCR - a2h
+ * 8. Poll for I2CSR[MBB] to get set.
+ * 9. Issue read to I2CDR.
+ * 10. Poll for I2CSR[MIF] to be set.
+ * 11. I2CCR - 82h
+ * 12. Workaround complete. Skip the next steps.
+ * 13. Issue read to I2CDR.
+ * 14. Poll for I2CSR[MIF] to be set.
+ * 15. I2CCR - 80h
+ */
+static void mpc_i2c_fixup_A004447(struct mpc_i2c *i2c)
+{
+ int ret;
+ u32 val;
+
+ writeccr(i2c, CCR_MEN | CCR_MSTA);
+ ret = i2c_mpc_wait_sr(i2c, CSR_MBB);
+ if (ret) {
+ dev_err(i2c->dev, "timeout waiting for CSR_MBB\n");
+ return;
+ }
+
+ val = readb(i2c->base + MPC_I2C_SR);
+
+ if (val & CSR_MAL) {
+ writeccr(i2c, 0x00);
+ writeccr(i2c, CCR_MSTA | CCR_RSVD);
+ writeccr(i2c, CCR_MEN | CCR_MSTA | CCR_RSVD);
+ ret = i2c_mpc_wait_sr(i2c, CSR_MBB);
+ if (ret) {
+ dev_err(i2c->dev, "timeout waiting for CSR_MBB\n");
+ return;
+ }
+ val = readb(i2c->base + MPC_I2C_DR);
+ ret = i2c_mpc_wait_sr(i2c, CSR_MIF);
+ if (ret) {
+ dev_err(i2c->dev, "timeout waiting for CSR_MIF\n");
+ return;
+ }
+ writeccr(i2c, CCR_MEN | CCR_RSVD);
+ } else {
+ val = readb(i2c->base + MPC_I2C_DR);
+ ret = i2c_mpc_wait_sr(i2c, CSR_MIF);
+ if (ret) {
+ dev_err(i2c->dev, "timeout waiting for CSR_MIF\n");
+ return;
+ }
+ writeccr(i2c, CCR_MEN);
+ }
+}
+
#if defined(CONFIG_PPC_MPC52xx) || defined(CONFIG_PPC_MPC512x)
static const struct mpc_i2c_divider mpc_i2c_dividers_52xx[] = {
{20, 0x20}, {22, 0x21}, {24, 0x22}, {26, 0x23},
@@ -670,7 +748,10 @@ static int fsl_i2c_bus_recovery(struct i2c_adapter *adap)
{
struct mpc_i2c *i2c = i2c_get_adapdata(adap);
- mpc_i2c_fixup(i2c);
+ if (i2c->has_errata_A004447)
+ mpc_i2c_fixup_A004447(i2c);
+ else
+ mpc_i2c_fixup(i2c);
return 0;
}
@@ -767,6 +848,9 @@ static int fsl_i2c_probe(struct platform_device *op)
}
dev_info(i2c->dev, "timeout %u us\n", mpc_ops.timeout * 1000000 / HZ);
+ if (of_property_read_bool(op->dev.of_node, "fsl,i2c-erratum-a004447"))
+ i2c->has_errata_A004447 = true;
+
i2c->adap = mpc_ops;
scnprintf(i2c->adap.name, sizeof(i2c->adap.name),
"MPC adapter (%s)", of_node_full_name(op->dev.of_node));
--
2.31.1
