From f553b79c03f0dbd52f6f03abe8233a2bef8cbd0d Mon Sep 17 00:00:00 2001 From: Ben Skeggs Date: Wed, 21 Dec 2011 18:09:12 +1000 Subject: [PATCH] drm/nouveau/i2c: handle bit-banging ourselves i2c-algo-bit doesn't actually work very well on one card I have access to (NVS 300), random single-bit errors occur most of the time - what we're doing now is closer to what xf86i2c.c does. The original plan was to figure out why i2c-algo-bit fails on the NVS 300, and fix it. However, while investigating I discovered i2c-algo-bit calls cond_resched(), which makes it a bad idea for us to be using as we execute VBIOS scripts from a tasklet, and there may very well be i2c transfers as a result. So, since I already wrote this code in userspace to track down the NVS 300 bug, and it's not really much code - lets use it. Signed-off-by: Ben Skeggs --- drivers/gpu/drm/nouveau/nouveau_i2c.c | 199 +++++++++++++++++++++++--- drivers/gpu/drm/nouveau/nouveau_i2c.h | 1 - 2 files changed, 178 insertions(+), 22 deletions(-) diff --git a/drivers/gpu/drm/nouveau/nouveau_i2c.c b/drivers/gpu/drm/nouveau/nouveau_i2c.c index 116ef3193fc..820ae7f5204 100644 --- a/drivers/gpu/drm/nouveau/nouveau_i2c.c +++ b/drivers/gpu/drm/nouveau/nouveau_i2c.c @@ -29,6 +29,10 @@ #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) { @@ -109,6 +113,175 @@ 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 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, @@ -211,10 +384,12 @@ nouveau_i2c_init(struct drm_device *dev) case 0: /* NV04:NV50 */ port->drive = entry[0]; port->sense = entry[1]; + port->adapter.algo = &i2c_bit_algo; break; case 4: /* NV4E */ port->drive = 0x600800 + entry[1]; port->sense = port->drive; + port->adapter.algo = &i2c_bit_algo; break; case 5: /* NV50- */ port->drive = entry[0] & 0x0f; @@ -227,6 +402,7 @@ nouveau_i2c_init(struct drm_device *dev) port->drive = 0x00d014 + (port->drive * 0x20); port->sense = port->drive; } + port->adapter.algo = &i2c_bit_algo; break; case 6: /* NV50- DP AUX */ port->drive = entry[0]; @@ -237,7 +413,7 @@ nouveau_i2c_init(struct drm_device *dev) break; } - if (!port->adapter.algo && !port->drive) { + if (!port->adapter.algo) { NV_ERROR(dev, "I2C%d: type %d index %x/%x unknown\n", i, port->type, port->drive, port->sense); kfree(port); @@ -253,26 +429,7 @@ nouveau_i2c_init(struct drm_device *dev) port->dcb = ROM32(entry[0]); i2c_set_adapdata(&port->adapter, i2c); - if (port->adapter.algo != &nouveau_dp_i2c_algo) { - port->adapter.algo_data = &port->bit; - port->bit.udelay = 40; - port->bit.timeout = usecs_to_jiffies(5000); - 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); - } - + 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 1d083893a4d..4d2e4e9031b 100644 --- a/drivers/gpu/drm/nouveau/nouveau_i2c.h +++ b/drivers/gpu/drm/nouveau/nouveau_i2c.h @@ -34,7 +34,6 @@ 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; -- 2.46.0