[PATCH v5 10/10] drm/bridge: it6505: add I2C functionality on AUX
Hermes Wu
Hermes.Wu at ite.com.tw
Tue Oct 1 06:45:50 UTC 2024
From: Hermes Wu <Hermes.wu at ite.com.tw>
DisplayPort AUX protocol supports I2C transport which is capable of reading EDID or supports MCCS.
In drm_dp_helper, drm_dp_i2c_xfer() packs I2C requests into a sequence of AUX requests.
it6505_aux_i2c_operation() is implemented to match drm_dp_i2c_xfer() behavior.
it6505_aux_i2c_transfer() adds I2C functionality for it6505_aux_transfer().
Signed-off-by: Hermes Wu <Hermes.wu at ite.com.tw>
---
drivers/gpu/drm/bridge/ite-it6505.c | 177 +++++++++++++++++++++++++++-
1 file changed, 175 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
index 2bf177a55daf..f03923bff3d9 100644
--- a/drivers/gpu/drm/bridge/ite-it6505.c
+++ b/drivers/gpu/drm/bridge/ite-it6505.c
@@ -267,6 +267,18 @@
#define REG_SSC_CTRL1 0x189
#define REG_SSC_CTRL2 0x18A
+#define REG_AUX_USER_CTRL 0x190
+#define EN_USER_AUX BIT(0)
+#define USER_AUX_DONE BIT(1)
+#define AUX_EVENT BIT(4)
+
+#define REG_AUX_USER_DATA_REC 0x191
+#define M_AUX_IN_REC 0xF0
+#define M_AUX_OUT_REC 0x0F
+
+#define REG_AUX_USER_REPLY 0x19A
+#define REG_AUX_USER_RXB(n) (n + 0x19B)
+
#define RBR DP_LINK_BW_1_62
#define HBR DP_LINK_BW_2_7
#define HBR2 DP_LINK_BW_5_4
@@ -302,6 +314,8 @@
#define MAX_EQ_LEVEL 0x03
#define AUX_WAIT_TIMEOUT_MS 15
#define AUX_FIFO_MAX_SIZE 16
+#define AUX_I2C_MAX_SIZE 4
+#define AUX_I2C_DEFER_RETRY 4
#define PIXEL_CLK_DELAY 1
#define PIXEL_CLK_INVERSE 0
#define ADJUST_PHASE_THRESHOLD 80000
@@ -324,7 +338,12 @@
enum aux_cmd_type {
CMD_AUX_NATIVE_READ = 0x0,
CMD_AUX_NATIVE_WRITE = 0x5,
+ CMD_AUX_GI2C_ADR = 0x08,
+ CMD_AUX_GI2C_READ = 0x09,
+ CMD_AUX_GI2C_WRITE = 0x0A,
CMD_AUX_I2C_EDID_READ = 0xB,
+ CMD_AUX_I2C_READ = 0x0D,
+ CMD_AUX_I2C_WRITE = 0x0C,
/* KSV read with AUX FIFO extend from CMD_AUX_NATIVE_READ*/
CMD_AUX_GET_KSV_LIST = 0x10,
@@ -1106,6 +1125,161 @@ static ssize_t it6505_aux_do_transfer(struct it6505 *it6505,
return ret;
}
+static bool it6505_aux_i2c_reply_defer(u8 reply)
+{
+ if (reply == DP_AUX_NATIVE_REPLY_DEFER || reply == DP_AUX_I2C_REPLY_DEFER)
+ return true;
+ return false;
+}
+
+static bool it6505_aux_i2c_reply_nack(u8 reply)
+{
+ if (reply == DP_AUX_NATIVE_REPLY_NACK || reply == DP_AUX_I2C_REPLY_NACK)
+ return true;
+ return false;
+}
+
+static int it6505_aux_i2c_wait(struct it6505 *it6505, u8 *reply)
+{
+ int err;
+ unsigned long timeout;
+ struct device *dev = it6505->dev;
+
+ timeout = jiffies + msecs_to_jiffies(AUX_WAIT_TIMEOUT_MS) + 1;
+
+ do {
+ if (it6505_read(it6505, REG_AUX_USER_CTRL) & AUX_EVENT)
+ break;
+ if (time_after(jiffies, timeout)) {
+ dev_err(dev, "Timed out waiting AUX I2C, BUSY = %X\n",
+ it6505_aux_op_finished(it6505));
+ err = -ETIMEDOUT;
+ goto end_aux_i2c_wait;
+ }
+ usleep_range(300, 800);
+ } while (!it6505_aux_op_finished(it6505));
+
+ *reply = it6505_read(it6505, REG_AUX_USER_REPLY) >> 4;
+
+ if (*reply == 0)
+ goto end_aux_i2c_wait;
+
+ if (it6505_aux_i2c_reply_defer(*reply))
+ err = -EBUSY;
+ else if (it6505_aux_i2c_reply_nack(*reply))
+ err = -ENXIO;
+
+end_aux_i2c_wait:
+ it6505_set_bits(it6505, REG_AUX_USER_CTRL, USER_AUX_DONE, USER_AUX_DONE);
+ return err;
+}
+
+static int it6505_aux_i2c_readb(struct it6505 *it6505, u8 *buf, size_t size, u8 *reply)
+{
+ int ret, i;
+ int retry;
+
+ for (retry = 0; retry < AUX_I2C_DEFER_RETRY; retry++) {
+ it6505_write(it6505, REG_AUX_CMD_REQ, CMD_AUX_GI2C_READ);
+
+ ret = it6505_aux_i2c_wait(it6505, reply);
+ if (it6505_aux_i2c_reply_defer(*reply))
+ continue;
+ if (ret >= 0)
+ break;
+ }
+
+ for (i = 0; i < size; i++)
+ buf[i] = it6505_read(it6505, REG_AUX_USER_RXB(0 + i));
+
+ return size;
+}
+
+static int it6505_aux_i2c_writeb(struct it6505 *it6505, u8 *buf, size_t size, u8 *reply)
+{
+ int i, ret;
+ int retry;
+
+ for (i = 0; i < size; i++)
+ it6505_write(it6505, REG_AUX_OUT_DATA0 + i, buf[i]);
+
+ for (retry = 0; retry < AUX_I2C_DEFER_RETRY; retry++) {
+ it6505_write(it6505, REG_AUX_CMD_REQ, CMD_AUX_GI2C_WRITE);
+
+ ret = it6505_aux_i2c_wait(it6505, reply);
+ if (it6505_aux_i2c_reply_defer(*reply))
+ continue;
+ if (ret >= 0)
+ break;
+ }
+ return size;
+}
+
+static ssize_t it6505_aux_i2c_operation(struct it6505 *it6505,
+ struct drm_dp_aux_msg *msg)
+{
+ int ret;
+ ssize_t request_size, data_cnt = 0;
+ u8 *buffer = msg->buffer;
+
+ /* set AUX user mode */
+ it6505_set_bits(it6505, REG_AUX_CTRL,
+ AUX_USER_MODE | AUX_NO_SEGMENT_WR, AUX_USER_MODE);
+ it6505_set_bits(it6505, REG_AUX_USER_CTRL, EN_USER_AUX, EN_USER_AUX);
+ /* clear AUX FIFO */
+ it6505_set_bits(it6505, REG_AUX_CTRL,
+ AUX_EN_FIFO_READ | CLR_EDID_FIFO,
+ AUX_EN_FIFO_READ | CLR_EDID_FIFO);
+
+ it6505_set_bits(it6505, REG_AUX_CTRL,
+ AUX_EN_FIFO_READ | CLR_EDID_FIFO, 0x00);
+
+ it6505_write(it6505, REG_AUX_ADR_0_7, 0x00);
+ it6505_write(it6505, REG_AUX_ADR_8_15, msg->address << 1);
+
+ if (msg->size == 0) {
+ /* IIC Start/STOP dummy write */
+ it6505_write(it6505, REG_AUX_ADR_16_19, msg->request);
+ it6505_write(it6505, REG_AUX_CMD_REQ, CMD_AUX_GI2C_ADR);
+ ret = it6505_aux_i2c_wait(it6505, &msg->reply);
+ goto end_aux_i2c_transfer;
+ }
+
+ /* IIC data transfer */
+ data_cnt = 0;
+ do {
+ request_size = min_t(ssize_t, msg->size - data_cnt, AUX_I2C_MAX_SIZE);
+ it6505_write(it6505, REG_AUX_ADR_16_19,
+ msg->request | ((request_size - 1) << 4));
+ if ((msg->request & DP_AUX_I2C_READ) == DP_AUX_I2C_READ)
+ ret = it6505_aux_i2c_readb(it6505, &buffer[data_cnt],
+ request_size, &msg->reply);
+ else
+ ret = it6505_aux_i2c_writeb(it6505, &buffer[data_cnt],
+ request_size, &msg->reply);
+
+ if (ret < 0)
+ goto end_aux_i2c_transfer;
+
+ data_cnt += request_size;
+ } while (data_cnt < msg->size);
+ ret = data_cnt;
+end_aux_i2c_transfer:
+
+ it6505_set_bits(it6505, REG_AUX_USER_CTRL, EN_USER_AUX, 0);
+ it6505_set_bits(it6505, REG_AUX_CTRL, AUX_USER_MODE, 0);
+ return ret;
+}
+
+static ssize_t it6505_aux_i2c_transfer(struct drm_dp_aux *aux,
+ struct drm_dp_aux_msg *msg)
+{
+ struct it6505 *it6505 = container_of(aux, struct it6505, aux);
+
+ guard(mutex)(&it6505->aux_lock);
+ return it6505_aux_i2c_operation(it6505, msg);
+}
+
static ssize_t it6505_aux_transfer(struct drm_dp_aux *aux,
struct drm_dp_aux_msg *msg)
{
@@ -1115,9 +1289,8 @@ static ssize_t it6505_aux_transfer(struct drm_dp_aux *aux,
int ret;
enum aux_cmd_reply reply;
- /* IT6505 doesn't support arbitrary I2C read / write. */
if (is_i2c)
- return -EINVAL;
+ return it6505_aux_i2c_transfer(aux, msg);
switch (msg->request) {
case DP_AUX_NATIVE_READ:
--
2.34.1
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