[PATCH v2] drm/sun4i: hdmi: Implement I2C adapter for A10s DDC bus

From: Jonathan Liu
Date: Mon Jun 12 2017 - 01:51:46 EST

The drm_get_edid function should be used instead of drm_do_get_edid by
exposing the DDC bus as an I2C adapter. Implement this for A10s.

Signed-off-by: Jonathan Liu <net147@xxxxxxxxx>
---
Changes for v2:
- Rebased against Maxime's sunxi-drm/for-next branch
- Fix up error paths in sun4i_hdmi_bind so that the I2C adapter is deleted if
any of the calls after the I2C adapter is created fails
- Remove unnecessary includes in sun4i_hdmi_i2c.c

drivers/gpu/drm/sun4i/Makefile | 1 +
drivers/gpu/drm/sun4i/sun4i_hdmi.h | 11 ++-
drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c | 103 +++------------------
drivers/gpu/drm/sun4i/sun4i_hdmi_i2c.c | 163 +++++++++++++++++++++++++++++++++
4 files changed, 189 insertions(+), 89 deletions(-)
create mode 100644 drivers/gpu/drm/sun4i/sun4i_hdmi_i2c.c

diff --git a/drivers/gpu/drm/sun4i/Makefile b/drivers/gpu/drm/sun4i/Makefile
index e29fd3a2ba9c..43c753cafc88 100644
--- a/drivers/gpu/drm/sun4i/Makefile
+++ b/drivers/gpu/drm/sun4i/Makefile
@@ -2,6 +2,7 @@ sun4i-drm-y += sun4i_drv.o
sun4i-drm-y += sun4i_framebuffer.o

sun4i-drm-hdmi-y += sun4i_hdmi_enc.o
+sun4i-drm-hdmi-y += sun4i_hdmi_i2c.o
sun4i-drm-hdmi-y += sun4i_hdmi_ddc_clk.o
sun4i-drm-hdmi-y += sun4i_hdmi_tmds_clk.o

diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi.h b/drivers/gpu/drm/sun4i/sun4i_hdmi.h
index 2f2f2ff1ea63..4c01dbe89cd9 100644
--- a/drivers/gpu/drm/sun4i/sun4i_hdmi.h
+++ b/drivers/gpu/drm/sun4i/sun4i_hdmi.h
@@ -97,6 +97,7 @@
#define SUN4I_HDMI_DDC_CTRL_START_CMD BIT(30)
#define SUN4I_HDMI_DDC_CTRL_FIFO_DIR_MASK BIT(8)
#define SUN4I_HDMI_DDC_CTRL_FIFO_DIR_READ (0 << 8)
+#define SUN4I_HDMI_DDC_CTRL_FIFO_DIR_WRITE (1 << 8)
#define SUN4I_HDMI_DDC_CTRL_RESET BIT(0)

#define SUN4I_HDMI_DDC_ADDR_REG 0x504
@@ -105,6 +106,10 @@
#define SUN4I_HDMI_DDC_ADDR_OFFSET(off) (((off) & 0xff) << 8)
#define SUN4I_HDMI_DDC_ADDR_SLAVE(addr) ((addr) & 0xff)

+#define SUN4I_HDMI_DDC_INTERRUPT_STATUS_REG 0x50c
+#define SUN4I_HDMI_DDC_INTERRUPT_STATUS_FIFO_REQUEST BIT(4)
+#define SUN4I_HDMI_DDC_INTERRUPT_STATUS_TRANSFER_COMPLETE BIT(0)
+
#define SUN4I_HDMI_DDC_FIFO_CTRL_REG 0x510
#define SUN4I_HDMI_DDC_FIFO_CTRL_CLEAR BIT(31)

@@ -112,7 +117,8 @@
#define SUN4I_HDMI_DDC_BYTE_COUNT_REG 0x51c

#define SUN4I_HDMI_DDC_CMD_REG 0x520
-#define SUN4I_HDMI_DDC_CMD_EXPLICIT_EDDC_READ 6
+#define SUN4I_HDMI_DDC_CMD_IMPLICIT_WRITE 3
+#define SUN4I_HDMI_DDC_CMD_IMPLICIT_READ 5

#define SUN4I_HDMI_DDC_CLK_REG 0x528
#define SUN4I_HDMI_DDC_CLK_M(m) (((m) & 0x7) << 3)
@@ -146,6 +152,8 @@ struct sun4i_hdmi {
struct clk *ddc_clk;
struct clk *tmds_clk;

+ struct i2c_adapter *i2c;
+
struct sun4i_drv *drv;

bool hdmi_monitor;
@@ -153,5 +161,6 @@ struct sun4i_hdmi {

int sun4i_ddc_create(struct sun4i_hdmi *hdmi, struct clk *clk);
int sun4i_tmds_create(struct sun4i_hdmi *hdmi);
+int sun4i_hdmi_i2c_create(struct sun4i_hdmi *hdmi);

#endif /* _SUN4I_HDMI_H_ */
diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
index d3398f6250ef..2a8c0b14eabc 100644
--- a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
+++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
@@ -29,8 +29,6 @@
#include "sun4i_hdmi.h"
#include "sun4i_tcon.h"

-#define DDC_SEGMENT_ADDR 0x30
-
static inline struct sun4i_hdmi *
drm_encoder_to_sun4i_hdmi(struct drm_encoder *encoder)
{
@@ -184,93 +182,13 @@ static const struct drm_encoder_funcs sun4i_hdmi_funcs = {
.destroy = drm_encoder_cleanup,
};

-static int sun4i_hdmi_read_sub_block(struct sun4i_hdmi *hdmi,
- unsigned int blk, unsigned int offset,
- u8 *buf, unsigned int count)
-{
- unsigned long reg;
- int i;
-
- reg = readl(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
- reg &= ~SUN4I_HDMI_DDC_CTRL_FIFO_DIR_MASK;
- writel(reg | SUN4I_HDMI_DDC_CTRL_FIFO_DIR_READ,
- hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
-
- writel(SUN4I_HDMI_DDC_ADDR_SEGMENT(offset >> 8) |
- SUN4I_HDMI_DDC_ADDR_EDDC(DDC_SEGMENT_ADDR << 1) |
- SUN4I_HDMI_DDC_ADDR_OFFSET(offset) |
- SUN4I_HDMI_DDC_ADDR_SLAVE(DDC_ADDR),
- hdmi->base + SUN4I_HDMI_DDC_ADDR_REG);
-
- reg = readl(hdmi->base + SUN4I_HDMI_DDC_FIFO_CTRL_REG);
- writel(reg | SUN4I_HDMI_DDC_FIFO_CTRL_CLEAR,
- hdmi->base + SUN4I_HDMI_DDC_FIFO_CTRL_REG);
-
- writel(count, hdmi->base + SUN4I_HDMI_DDC_BYTE_COUNT_REG);
- writel(SUN4I_HDMI_DDC_CMD_EXPLICIT_EDDC_READ,
- hdmi->base + SUN4I_HDMI_DDC_CMD_REG);
-
- reg = readl(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
- writel(reg | SUN4I_HDMI_DDC_CTRL_START_CMD,
- hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
-
- if (readl_poll_timeout(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG, reg,
- !(reg & SUN4I_HDMI_DDC_CTRL_START_CMD),
- 100, 100000))
- return -EIO;
-
- for (i = 0; i < count; i++)
- buf[i] = readb(hdmi->base + SUN4I_HDMI_DDC_FIFO_DATA_REG);
-
- return 0;
-}
-
-static int sun4i_hdmi_read_edid_block(void *data, u8 *buf, unsigned int blk,
- size_t length)
-{
- struct sun4i_hdmi *hdmi = data;
- int retry = 2, i;
-
- do {
- for (i = 0; i < length; i += SUN4I_HDMI_DDC_FIFO_SIZE) {
- unsigned char offset = blk * EDID_LENGTH + i;
- unsigned int count = min((unsigned int)SUN4I_HDMI_DDC_FIFO_SIZE,
- length - i);
- int ret;
-
- ret = sun4i_hdmi_read_sub_block(hdmi, blk, offset,
- buf + i, count);
- if (ret)
- return ret;
- }
- } while (!drm_edid_block_valid(buf, blk, true, NULL) && (retry--));
-
- return 0;
-}
-
static int sun4i_hdmi_get_modes(struct drm_connector *connector)
{
struct sun4i_hdmi *hdmi = drm_connector_to_sun4i_hdmi(connector);
- unsigned long reg;
struct edid *edid;
int ret;

- /* Reset i2c controller */
- writel(SUN4I_HDMI_DDC_CTRL_ENABLE | SUN4I_HDMI_DDC_CTRL_RESET,
- hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
- if (readl_poll_timeout(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG, reg,
- !(reg & SUN4I_HDMI_DDC_CTRL_RESET),
- 100, 2000))
- return -EIO;
-
- writel(SUN4I_HDMI_DDC_LINE_CTRL_SDA_ENABLE |
- SUN4I_HDMI_DDC_LINE_CTRL_SCL_ENABLE,
- hdmi->base + SUN4I_HDMI_DDC_LINE_CTRL_REG);
-
- clk_prepare_enable(hdmi->ddc_clk);
- clk_set_rate(hdmi->ddc_clk, 100000);
-
- edid = drm_do_get_edid(connector, sun4i_hdmi_read_edid_block, hdmi);
+ edid = drm_get_edid(connector, hdmi->i2c);
if (!edid)
return 0;

@@ -282,8 +200,6 @@ static int sun4i_hdmi_get_modes(struct drm_connector *connector)
ret = drm_add_edid_modes(connector, edid);
kfree(edid);

- clk_disable_unprepare(hdmi->ddc_clk);
-
return ret;
}

@@ -413,6 +329,12 @@ static int sun4i_hdmi_bind(struct device *dev, struct device *master,
return ret;
}

+ ret = sun4i_hdmi_i2c_create(hdmi);
+ if (ret) {
+ dev_err(dev, "Couldn't create the HDMI I2C adapter\n");
+ return ret;
+ }
+
drm_encoder_helper_add(&hdmi->encoder,
&sun4i_hdmi_helper_funcs);
ret = drm_encoder_init(drm,
@@ -422,13 +344,15 @@ static int sun4i_hdmi_bind(struct device *dev, struct device *master,
NULL);
if (ret) {
dev_err(dev, "Couldn't initialise the HDMI encoder\n");
- return ret;
+ goto err_del_i2c_adapter;
}

hdmi->encoder.possible_crtcs = drm_of_find_possible_crtcs(drm,
dev->of_node);
- if (!hdmi->encoder.possible_crtcs)
- return -EPROBE_DEFER;
+ if (!hdmi->encoder.possible_crtcs) {
+ ret = -EPROBE_DEFER;
+ goto err_del_i2c_adapter;
+ }

drm_connector_helper_add(&hdmi->connector,
&sun4i_hdmi_connector_helper_funcs);
@@ -451,6 +375,8 @@ static int sun4i_hdmi_bind(struct device *dev, struct device *master,

err_cleanup_connector:
drm_encoder_cleanup(&hdmi->encoder);
+err_del_i2c_adapter:
+ i2c_del_adapter(hdmi->i2c);
return ret;
}

@@ -461,6 +387,7 @@ static void sun4i_hdmi_unbind(struct device *dev, struct device *master,

drm_connector_cleanup(&hdmi->connector);
drm_encoder_cleanup(&hdmi->encoder);
+ i2c_del_adapter(hdmi->i2c);
}

static const struct component_ops sun4i_hdmi_ops = {
diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_i2c.c b/drivers/gpu/drm/sun4i/sun4i_hdmi_i2c.c
new file mode 100644
index 000000000000..389b770be09b
--- /dev/null
+++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_i2c.c
@@ -0,0 +1,163 @@
+/*
+ * Copyright (C) 2017 Jonathan Liu
+ *
+ * Jonathan Liu <net147@xxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ */
+
+#include <linux/clk.h>
+#include <linux/i2c.h>
+#include <linux/iopoll.h>
+
+#include "sun4i_hdmi.h"
+
+static int xfer_msg_chunk(struct sun4i_hdmi *hdmi, struct i2c_msg *msg)
+{
+ u32 count = min_t(u32, msg->len, SUN4I_HDMI_DDC_FIFO_SIZE);
+ u32 reg;
+ int i;
+
+ reg = readl(hdmi->base + SUN4I_HDMI_DDC_FIFO_CTRL_REG);
+ writel(reg | SUN4I_HDMI_DDC_FIFO_CTRL_CLEAR,
+ hdmi->base + SUN4I_HDMI_DDC_FIFO_CTRL_REG);
+
+ writel(count, hdmi->base
+ + SUN4I_HDMI_DDC_BYTE_COUNT_REG);
+ writel(msg->flags & I2C_M_RD
+ ? SUN4I_HDMI_DDC_CMD_IMPLICIT_READ
+ : SUN4I_HDMI_DDC_CMD_IMPLICIT_WRITE,
+ hdmi->base + SUN4I_HDMI_DDC_CMD_REG);
+
+ reg = readl(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
+ writel(reg | SUN4I_HDMI_DDC_CTRL_START_CMD,
+ hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
+
+ if (!(msg->flags & I2C_M_RD)) {
+ for (i = 0; i < count; i++) {
+ writeb(*msg->buf++, hdmi->base
+ + SUN4I_HDMI_DDC_FIFO_DATA_REG);
+ --msg->len;
+ }
+ }
+
+ if (readl_poll_timeout(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG,
+ reg,
+ !(reg & SUN4I_HDMI_DDC_CTRL_START_CMD),
+ 100, 100000))
+ return -EIO;
+
+ reg = readl(hdmi->base + SUN4I_HDMI_DDC_INTERRUPT_STATUS_REG);
+ reg &= ~SUN4I_HDMI_DDC_INTERRUPT_STATUS_FIFO_REQUEST;
+
+ if (reg != SUN4I_HDMI_DDC_INTERRUPT_STATUS_TRANSFER_COMPLETE)
+ return -EIO;
+
+ if (msg->flags & I2C_M_RD) {
+ for (i = 0; i < count; i++) {
+ *msg->buf++ = readb(hdmi->base
+ + SUN4I_HDMI_DDC_FIFO_DATA_REG);
+ --msg->len;
+ }
+ }
+
+ return 0;
+}
+
+static int xfer_msg(struct sun4i_hdmi *hdmi, struct i2c_msg *msg)
+{
+ u32 reg;
+ int ret;
+
+ if (!msg->len)
+ return -EIO;
+
+ while (msg->len) {
+ reg = readl(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
+ reg &= ~SUN4I_HDMI_DDC_CTRL_FIFO_DIR_MASK;
+
+ writel(reg | (msg->flags & I2C_M_RD
+ ? SUN4I_HDMI_DDC_CTRL_FIFO_DIR_READ
+ : SUN4I_HDMI_DDC_CTRL_FIFO_DIR_WRITE),
+ hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
+
+ writel(SUN4I_HDMI_DDC_ADDR_SLAVE(msg->addr),
+ hdmi->base + SUN4I_HDMI_DDC_ADDR_REG);
+
+ ret = xfer_msg_chunk(hdmi, msg);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+static int sun4i_hdmi_i2c_xfer(struct i2c_adapter *adap,
+ struct i2c_msg *msgs, int num)
+{
+ struct sun4i_hdmi *hdmi = i2c_get_adapdata(adap);
+ u32 reg;
+ int err, ret = num;
+ int i;
+
+ /* Reset i2c controller */
+ writel(SUN4I_HDMI_DDC_CTRL_ENABLE | SUN4I_HDMI_DDC_CTRL_RESET,
+ hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
+ if (readl_poll_timeout(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG, reg,
+ !(reg & SUN4I_HDMI_DDC_CTRL_RESET),
+ 100, 2000))
+ return -EIO;
+
+ writel(SUN4I_HDMI_DDC_LINE_CTRL_SDA_ENABLE |
+ SUN4I_HDMI_DDC_LINE_CTRL_SCL_ENABLE,
+ hdmi->base + SUN4I_HDMI_DDC_LINE_CTRL_REG);
+
+ clk_prepare_enable(hdmi->ddc_clk);
+ clk_set_rate(hdmi->ddc_clk, 100000);
+
+ for (i = 0; i < num; i++) {
+ err = xfer_msg(hdmi, &msgs[i]);
+ if (err) {
+ ret = err;
+ break;
+ }
+ }
+
+ clk_disable_unprepare(hdmi->ddc_clk);
+ return ret;
+}
+
+static u32 sun4i_hdmi_i2c_func(struct i2c_adapter *adap)
+{
+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm sun4i_hdmi_i2c_algorithm = {
+ .master_xfer = sun4i_hdmi_i2c_xfer,
+ .functionality = sun4i_hdmi_i2c_func,
+};
+
+static struct i2c_adapter sun4i_hdmi_i2c_adapter = {
+ .owner = THIS_MODULE,
+ .class = I2C_CLASS_DDC,
+ .algo = &sun4i_hdmi_i2c_algorithm,
+ .name = "sun4i_hdmi_i2c adapter",
+};
+
+int sun4i_hdmi_i2c_create(struct sun4i_hdmi *hdmi)
+{
+ int ret = 0;
+
+ i2c_set_adapdata(&sun4i_hdmi_i2c_adapter, hdmi);
+
+ ret = i2c_add_adapter(&sun4i_hdmi_i2c_adapter);
+ if (ret)
+ return ret;
+
+ hdmi->i2c = &sun4i_hdmi_i2c_adapter;
+
+ return ret;
+}
--
2.12.2