From: Chris Packham chris.packham@alliedtelesis.co.nz
[ Upstream commit drivers/i2c/busses/i2c-mpc.c ]
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.packham@alliedtelesis.co.nz Signed-off-by: Wolfram Sang wsa@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/i2c/busses/i2c-mpc.c | 79 +++++++++++++++++++++++++++++++++++- 1 file changed, 78 insertions(+), 1 deletion(-)
diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c index 6a0d55e9e8e3..af349661fd76 100644 --- a/drivers/i2c/busses/i2c-mpc.c +++ b/drivers/i2c/busses/i2c-mpc.c @@ -23,6 +23,7 @@
#include <linux/clk.h> #include <linux/io.h> +#include <linux/iopoll.h> #include <linux/fsl_devices.h> #include <linux/i2c.h> #include <linux/interrupt.h> @@ -49,6 +50,7 @@ #define CCR_MTX 0x10 #define CCR_TXAK 0x08 #define CCR_RSTA 0x04 +#define CCR_RSVD 0x02
#define CSR_MCF 0x80 #define CSR_MAAS 0x40 @@ -70,6 +72,7 @@ struct mpc_i2c { u8 fdr, dfsrr; #endif struct clk *clk_per; + bool has_errata_A004447; };
struct mpc_i2c_divider { @@ -176,6 +179,75 @@ static int i2c_wait(struct mpc_i2c *i2c, unsigned timeout, int writing) return 0; }
+static int i2c_mpc_wait_sr(struct mpc_i2c *i2c, int mask) +{ + void __iomem *addr = i2c->base + MPC_I2C_SR; + u8 val; + + return readb_poll_timeout(addr, val, val & mask, 0, 100); +} + +/* + * 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}, @@ -641,7 +713,10 @@ 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; } @@ -745,6 +820,8 @@ static int fsl_i2c_probe(struct platform_device *op) dev_info(i2c->dev, "timeout %u us\n", mpc_ops.timeout * 1000000 / HZ);
platform_set_drvdata(op, i2c); + if (of_property_read_bool(op->dev.of_node, "fsl,i2c-erratum-a004447")) + i2c->has_errata_A004447 = true;
i2c->adap = mpc_ops; of_address_to_resource(op->dev.of_node, 0, &res);