drm/nouveau/i2c: resume use of i2c-algo-bit, rather than custom stack

Previous issues with i2c-algo-bit have now been resolved.

This is a revert of f553b79c03f0dbd52f6f03abe8233a2bef8cbd0d mostly,
due to fixes in the i2c core repairing the original issue, this code
isn't required and was causing regressions.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reported-by: Nick Bowler <nbowler@elliptictech.com>
Tested-by: Nick Bowler <nbowler@elliptictech.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

2 files changed, 22 insertions, 178 deletions

diff --git a/drivers/gpu/drm/nouveau/nouveau_i2c.c b/drivers/gpu/drm/nouveau/nouveau_i2c.c
index e2be95af2e52..77e564667b5c 100644
--- a/drivers/gpu/drm/nouveau/nouveau_i2c.c
+++ b/drivers/gpu/drm/nouveau/nouveau_i2c.c
@@ -29,10 +29,6 @@
 #include "nouveau_i2c.h"
 #include "nouveau_hw.h"
 
-#define T_TIMEOUT  2200000
-#define T_RISEFALL 1000
-#define T_HOLD     5000
-
 static void
 i2c_drive_scl(void *data, int state)
 {
@@ -113,175 +109,6 @@ i2c_sense_sda(void *data)
         return 0;
 }
 
-static void
-i2c_delay(struct nouveau_i2c_chan *port, u32 nsec)
-{
-        udelay((nsec + 500) / 1000);
-}
-
-static bool
-i2c_raise_scl(struct nouveau_i2c_chan *port)
-{
-        u32 timeout = T_TIMEOUT / T_RISEFALL;
-
-        i2c_drive_scl(port, 1);
-        do {
-                i2c_delay(port, T_RISEFALL);
-        } while (!i2c_sense_scl(port) && --timeout);
-
-        return timeout != 0;
-}
-
-static int
-i2c_start(struct nouveau_i2c_chan *port)
-{
-        int ret = 0;
-
-        port->state  = i2c_sense_scl(port);
-        port->state |= i2c_sense_sda(port) << 1;
-        if (port->state != 3) {
-                i2c_drive_scl(port, 0);
-                i2c_drive_sda(port, 1);
-                if (!i2c_raise_scl(port))
-                        ret = -EBUSY;
-        }
-
-        i2c_drive_sda(port, 0);
-        i2c_delay(port, T_HOLD);
-        i2c_drive_scl(port, 0);
-        i2c_delay(port, T_HOLD);
-        return ret;
-}
-
-static void
-i2c_stop(struct nouveau_i2c_chan *port)
-{
-        i2c_drive_scl(port, 0);
-        i2c_drive_sda(port, 0);
-        i2c_delay(port, T_RISEFALL);
-
-        i2c_drive_scl(port, 1);
-        i2c_delay(port, T_HOLD);
-        i2c_drive_sda(port, 1);
-        i2c_delay(port, T_HOLD);
-}
-
-static int
-i2c_bitw(struct nouveau_i2c_chan *port, int sda)
-{
-        i2c_drive_sda(port, sda);
-        i2c_delay(port, T_RISEFALL);
-
-        if (!i2c_raise_scl(port))
-                return -ETIMEDOUT;
-        i2c_delay(port, T_HOLD);
-
-        i2c_drive_scl(port, 0);
-        i2c_delay(port, T_HOLD);
-        return 0;
-}
-
-static int
-i2c_bitr(struct nouveau_i2c_chan *port)
-{
-        int sda;
-
-        i2c_drive_sda(port, 1);
-        i2c_delay(port, T_RISEFALL);
-
-        if (!i2c_raise_scl(port))
-                return -ETIMEDOUT;
-        i2c_delay(port, T_HOLD);
-
-        sda = i2c_sense_sda(port);
-
-        i2c_drive_scl(port, 0);
-        i2c_delay(port, T_HOLD);
-        return sda;
-}
-
-static int
-i2c_get_byte(struct nouveau_i2c_chan *port, u8 *byte, bool last)
-{
-        int i, bit;
-
-        *byte = 0;
-        for (i = 7; i >= 0; i--) {
-                bit = i2c_bitr(port);
-                if (bit < 0)
-                        return bit;
-                *byte |= bit << i;
-        }
-
-        return i2c_bitw(port, last ? 1 : 0);
-}
-
-static int
-i2c_put_byte(struct nouveau_i2c_chan *port, u8 byte)
-{
-        int i, ret;
-        for (i = 7; i >= 0; i--) {
-                ret = i2c_bitw(port, !!(byte & (1 << i)));
-                if (ret < 0)
-                        return ret;
-        }
-
-        ret = i2c_bitr(port);
-        if (ret == 1) /* nack */
-                ret = -EIO;
-        return ret;
-}
-
-static int
-i2c_addr(struct nouveau_i2c_chan *port, struct i2c_msg *msg)
-{
-        u32 addr = msg->addr << 1;
-        if (msg->flags & I2C_M_RD)
-                addr |= 1;
-        return i2c_put_byte(port, addr);
-}
-
-static int
-i2c_bit_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
-{
-        struct nouveau_i2c_chan *port = (struct nouveau_i2c_chan *)adap;
-        struct i2c_msg *msg = msgs;
-        int ret = 0, mcnt = num;
-
-        while (!ret && mcnt--) {
-                u8 remaining = msg->len;
-                u8 *ptr = msg->buf;
-
-                ret = i2c_start(port);
-                if (ret == 0)
-                        ret = i2c_addr(port, msg);
-
-                if (msg->flags & I2C_M_RD) {
-                        while (!ret && remaining--)
-                                ret = i2c_get_byte(port, ptr++, !remaining);
-                } else {
-                        while (!ret && remaining--)
-                                ret = i2c_put_byte(port, *ptr++);
-                }
-
-                msg++;
-        }
-
-        i2c_stop(port);
-        return (ret < 0) ? ret : num;
-}
-
-static u32
-i2c_bit_func(struct i2c_adapter *adap)
-{
-        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
-}
-
-const struct i2c_algorithm nouveau_i2c_bit_algo = {
-        .master_xfer = i2c_bit_xfer,
-        .functionality = i2c_bit_func
-};
-
 static const uint32_t nv50_i2c_port[] = {
         0x00e138, 0x00e150, 0x00e168, 0x00e180,
         0x00e254, 0x00e274, 0x00e764, 0x00e780,
@@ -384,12 +211,10 @@ nouveau_i2c_init(struct drm_device *dev)
                 case 0: /* NV04:NV50 */
                         port->drive = entry[0];
                         port->sense = entry[1];
-                        port->adapter.algo = &nouveau_i2c_bit_algo;
                         break;
                 case 4: /* NV4E */
                         port->drive = 0x600800 + entry[1];
                         port->sense = port->drive;
-                        port->adapter.algo = &nouveau_i2c_bit_algo;
                         break;
                 case 5: /* NV50- */
                         port->drive = entry[0] & 0x0f;
@@ -402,7 +227,6 @@ nouveau_i2c_init(struct drm_device *dev)
                                 port->drive = 0x00d014 + (port->drive * 0x20);
                                 port->sense = port->drive;
                         }
-                        port->adapter.algo = &nouveau_i2c_bit_algo;
                         break;
                 case 6: /* NV50- DP AUX */
                         port->drive = entry[0];
@@ -413,7 +237,7 @@ nouveau_i2c_init(struct drm_device *dev)
                         break;
                 }
 
-                if (!port->adapter.algo) {
+                if (!port->adapter.algo && !port->drive) {
                         NV_ERROR(dev, "I2C%d: type %d index %x/%x unknown\n",
                                  i, port->type, port->drive, port->sense);
                         kfree(port);
@@ -429,7 +253,26 @@ nouveau_i2c_init(struct drm_device *dev)
                 port->dcb = ROM32(entry[0]);
                 i2c_set_adapdata(&port->adapter, i2c);
 
-                ret = i2c_add_adapter(&port->adapter);
+                if (port->adapter.algo != &nouveau_dp_i2c_algo) {
+                        port->adapter.algo_data = &port->bit;
+                        port->bit.udelay = 10;
+                        port->bit.timeout = usecs_to_jiffies(2200);
+                        port->bit.data = port;
+                        port->bit.setsda = i2c_drive_sda;
+                        port->bit.setscl = i2c_drive_scl;
+                        port->bit.getsda = i2c_sense_sda;
+                        port->bit.getscl = i2c_sense_scl;
+
+                        i2c_drive_scl(port, 0);
+                        i2c_drive_sda(port, 1);
+                        i2c_drive_scl(port, 1);
+
+                        ret = i2c_bit_add_bus(&port->adapter);
+                } else {
+                        port->adapter.algo = &nouveau_dp_i2c_algo;
+                        ret = i2c_add_adapter(&port->adapter);
+                }
+
                 if (ret) {
                         NV_ERROR(dev, "I2C%d: failed register: %d\n", i, ret);
                         kfree(port);
diff --git a/drivers/gpu/drm/nouveau/nouveau_i2c.h b/drivers/gpu/drm/nouveau/nouveau_i2c.h
index 4d2e4e9031be..1d083893a4d7 100644
--- a/drivers/gpu/drm/nouveau/nouveau_i2c.h
+++ b/drivers/gpu/drm/nouveau/nouveau_i2c.h
@@ -34,6 +34,7 @@
 struct nouveau_i2c_chan {
         struct i2c_adapter adapter;
         struct drm_device *dev;
+        struct i2c_algo_bit_data bit;
         struct list_head head;
         u8  index;
         u8  type;