Commit 3b770017 authored by Wolfram Sang's avatar Wolfram Sang Committed by Wolfram Sang

i2c: rcar: handle RXDMA HW behaviour on Gen3

On Gen3, we can only do RXDMA once per transfer reliably. For that, we
must reset the device, then we can have RXDMA once. This patch
implements this. When there is no reset controller or the reset fails,
RXDMA will be blocked completely. Otherwise, it will be disabled after
the first RXDMA transfer. Based on a commit from the BSP by Hiromitsu
Yamasaki, yet completely refactored to handle multiple read messages
within one transfer.
Signed-off-by: default avatarWolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
parent 263fe5d4
...@@ -32,6 +32,7 @@ ...@@ -32,6 +32,7 @@
#include <linux/of_device.h> #include <linux/of_device.h>
#include <linux/platform_device.h> #include <linux/platform_device.h>
#include <linux/pm_runtime.h> #include <linux/pm_runtime.h>
#include <linux/reset.h>
#include <linux/slab.h> #include <linux/slab.h>
/* register offsets */ /* register offsets */
...@@ -111,8 +112,9 @@ ...@@ -111,8 +112,9 @@
#define ID_ARBLOST (1 << 3) #define ID_ARBLOST (1 << 3)
#define ID_NACK (1 << 4) #define ID_NACK (1 << 4)
/* persistent flags */ /* persistent flags */
#define ID_P_NO_RXDMA (1 << 30) /* HW forbids RXDMA sometimes */
#define ID_P_PM_BLOCKED (1 << 31) #define ID_P_PM_BLOCKED (1 << 31)
#define ID_P_MASK ID_P_PM_BLOCKED #define ID_P_MASK (ID_P_PM_BLOCKED | ID_P_NO_RXDMA)
enum rcar_i2c_type { enum rcar_i2c_type {
I2C_RCAR_GEN1, I2C_RCAR_GEN1,
...@@ -141,6 +143,8 @@ struct rcar_i2c_priv { ...@@ -141,6 +143,8 @@ struct rcar_i2c_priv {
struct dma_chan *dma_rx; struct dma_chan *dma_rx;
struct scatterlist sg; struct scatterlist sg;
enum dma_data_direction dma_direction; enum dma_data_direction dma_direction;
struct reset_control *rstc;
}; };
#define rcar_i2c_priv_to_dev(p) ((p)->adap.dev.parent) #define rcar_i2c_priv_to_dev(p) ((p)->adap.dev.parent)
...@@ -371,6 +375,11 @@ static void rcar_i2c_dma_unmap(struct rcar_i2c_priv *priv) ...@@ -371,6 +375,11 @@ static void rcar_i2c_dma_unmap(struct rcar_i2c_priv *priv)
dma_unmap_single(chan->device->dev, sg_dma_address(&priv->sg), dma_unmap_single(chan->device->dev, sg_dma_address(&priv->sg),
sg_dma_len(&priv->sg), priv->dma_direction); sg_dma_len(&priv->sg), priv->dma_direction);
/* Gen3 can only do one RXDMA per transfer and we just completed it */
if (priv->devtype == I2C_RCAR_GEN3 &&
priv->dma_direction == DMA_FROM_DEVICE)
priv->flags |= ID_P_NO_RXDMA;
priv->dma_direction = DMA_NONE; priv->dma_direction = DMA_NONE;
} }
...@@ -408,8 +417,9 @@ static void rcar_i2c_dma(struct rcar_i2c_priv *priv) ...@@ -408,8 +417,9 @@ static void rcar_i2c_dma(struct rcar_i2c_priv *priv)
unsigned char *buf; unsigned char *buf;
int len; int len;
/* Do not use DMA if it's not available or for messages < 8 bytes */ /* Do various checks to see if DMA is feasible at all */
if (IS_ERR(chan) || msg->len < 8 || !(msg->flags & I2C_M_DMA_SAFE)) if (IS_ERR(chan) || msg->len < 8 || !(msg->flags & I2C_M_DMA_SAFE) ||
(read && priv->flags & ID_P_NO_RXDMA))
return; return;
if (read) { if (read) {
...@@ -740,6 +750,25 @@ static void rcar_i2c_release_dma(struct rcar_i2c_priv *priv) ...@@ -740,6 +750,25 @@ static void rcar_i2c_release_dma(struct rcar_i2c_priv *priv)
} }
} }
/* I2C is a special case, we need to poll the status of a reset */
static int rcar_i2c_do_reset(struct rcar_i2c_priv *priv)
{
int i, ret;
ret = reset_control_reset(priv->rstc);
if (ret)
return ret;
for (i = 0; i < LOOP_TIMEOUT; i++) {
ret = reset_control_status(priv->rstc);
if (ret == 0)
return 0;
udelay(1);
}
return -ETIMEDOUT;
}
static int rcar_i2c_master_xfer(struct i2c_adapter *adap, static int rcar_i2c_master_xfer(struct i2c_adapter *adap,
struct i2c_msg *msgs, struct i2c_msg *msgs,
int num) int num)
...@@ -751,6 +780,16 @@ static int rcar_i2c_master_xfer(struct i2c_adapter *adap, ...@@ -751,6 +780,16 @@ static int rcar_i2c_master_xfer(struct i2c_adapter *adap,
pm_runtime_get_sync(dev); pm_runtime_get_sync(dev);
/* Gen3 needs a reset before allowing RXDMA once */
if (priv->devtype == I2C_RCAR_GEN3) {
priv->flags |= ID_P_NO_RXDMA;
if (!IS_ERR(priv->rstc)) {
ret = rcar_i2c_do_reset(priv);
if (ret == 0)
priv->flags &= ~ID_P_NO_RXDMA;
}
}
rcar_i2c_init(priv); rcar_i2c_init(priv);
ret = rcar_i2c_bus_barrier(priv); ret = rcar_i2c_bus_barrier(priv);
...@@ -921,6 +960,15 @@ static int rcar_i2c_probe(struct platform_device *pdev) ...@@ -921,6 +960,15 @@ static int rcar_i2c_probe(struct platform_device *pdev)
if (ret < 0) if (ret < 0)
goto out_pm_put; goto out_pm_put;
if (priv->devtype == I2C_RCAR_GEN3) {
priv->rstc = devm_reset_control_get_exclusive(&pdev->dev, NULL);
if (!IS_ERR(priv->rstc)) {
ret = reset_control_status(priv->rstc);
if (ret < 0)
priv->rstc = ERR_PTR(-ENOTSUPP);
}
}
/* Stay always active when multi-master to keep arbitration working */ /* Stay always active when multi-master to keep arbitration working */
if (of_property_read_bool(dev->of_node, "multi-master")) if (of_property_read_bool(dev->of_node, "multi-master"))
priv->flags |= ID_P_PM_BLOCKED; priv->flags |= ID_P_PM_BLOCKED;
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment