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 <bskeggs@redhat.com>hifive-unleashed-5.1
Ben Skeggs
parent
9e3b6b9907
commit
f553b79c03
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@ -29,6 +29,10 @@
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#include "nouveau_i2c.h"
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#include "nouveau_hw.h"
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#define T_TIMEOUT 2200000
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#define T_RISEFALL 1000
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#define T_HOLD 5000
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static void
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i2c_drive_scl(void *data, int state)
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{
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@ -109,6 +113,175 @@ i2c_sense_sda(void *data)
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return 0;
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}
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static void
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i2c_delay(struct nouveau_i2c_chan *port, u32 nsec)
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{
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udelay((nsec + 500) / 1000);
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}
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static bool
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i2c_raise_scl(struct nouveau_i2c_chan *port)
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{
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u32 timeout = T_TIMEOUT / T_RISEFALL;
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i2c_drive_scl(port, 1);
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do {
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i2c_delay(port, T_RISEFALL);
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} while (!i2c_sense_scl(port) && --timeout);
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return timeout != 0;
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}
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static int
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i2c_start(struct nouveau_i2c_chan *port)
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{
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int ret = 0;
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port->state = i2c_sense_scl(port);
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port->state |= i2c_sense_sda(port) << 1;
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if (port->state != 3) {
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i2c_drive_scl(port, 0);
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i2c_drive_sda(port, 1);
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if (!i2c_raise_scl(port))
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ret = -EBUSY;
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}
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i2c_drive_sda(port, 0);
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i2c_delay(port, T_HOLD);
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i2c_drive_scl(port, 0);
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i2c_delay(port, T_HOLD);
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return ret;
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}
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static void
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i2c_stop(struct nouveau_i2c_chan *port)
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{
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i2c_drive_scl(port, 0);
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i2c_drive_sda(port, 0);
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i2c_delay(port, T_RISEFALL);
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i2c_drive_scl(port, 1);
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i2c_delay(port, T_HOLD);
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i2c_drive_sda(port, 1);
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i2c_delay(port, T_HOLD);
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}
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static int
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i2c_bitw(struct nouveau_i2c_chan *port, int sda)
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{
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i2c_drive_sda(port, sda);
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i2c_delay(port, T_RISEFALL);
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if (!i2c_raise_scl(port))
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return -ETIMEDOUT;
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i2c_delay(port, T_HOLD);
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i2c_drive_scl(port, 0);
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i2c_delay(port, T_HOLD);
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return 0;
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}
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static int
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i2c_bitr(struct nouveau_i2c_chan *port)
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{
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int sda;
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i2c_drive_sda(port, 1);
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i2c_delay(port, T_RISEFALL);
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if (!i2c_raise_scl(port))
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return -ETIMEDOUT;
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i2c_delay(port, T_HOLD);
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sda = i2c_sense_sda(port);
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i2c_drive_scl(port, 0);
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i2c_delay(port, T_HOLD);
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return sda;
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}
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static int
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i2c_get_byte(struct nouveau_i2c_chan *port, u8 *byte, bool last)
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{
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int i, bit;
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*byte = 0;
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for (i = 7; i >= 0; i--) {
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bit = i2c_bitr(port);
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if (bit < 0)
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return bit;
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*byte |= bit << i;
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}
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return i2c_bitw(port, last ? 1 : 0);
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}
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static int
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i2c_put_byte(struct nouveau_i2c_chan *port, u8 byte)
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{
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int i, ret;
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for (i = 7; i >= 0; i--) {
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ret = i2c_bitw(port, !!(byte & (1 << i)));
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if (ret < 0)
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return ret;
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}
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ret = i2c_bitr(port);
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if (ret == 1) /* nack */
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ret = -EIO;
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return ret;
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}
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static int
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i2c_addr(struct nouveau_i2c_chan *port, struct i2c_msg *msg)
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{
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u32 addr = msg->addr << 1;
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if (msg->flags & I2C_M_RD)
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addr |= 1;
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return i2c_put_byte(port, addr);
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}
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static int
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i2c_bit_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
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{
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struct nouveau_i2c_chan *port = (struct nouveau_i2c_chan *)adap;
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struct i2c_msg *msg = msgs;
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int ret = 0, mcnt = num;
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while (!ret && mcnt--) {
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u8 remaining = msg->len;
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u8 *ptr = msg->buf;
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ret = i2c_start(port);
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if (ret == 0)
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ret = i2c_addr(port, msg);
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if (msg->flags & I2C_M_RD) {
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while (!ret && remaining--)
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ret = i2c_get_byte(port, ptr++, !remaining);
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} else {
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while (!ret && remaining--)
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ret = i2c_put_byte(port, *ptr++);
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}
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msg++;
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}
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i2c_stop(port);
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return (ret < 0) ? ret : num;
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}
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static u32
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i2c_bit_func(struct i2c_adapter *adap)
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{
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return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
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}
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const struct i2c_algorithm i2c_bit_algo = {
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.master_xfer = i2c_bit_xfer,
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.functionality = i2c_bit_func
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};
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static const uint32_t nv50_i2c_port[] = {
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0x00e138, 0x00e150, 0x00e168, 0x00e180,
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0x00e254, 0x00e274, 0x00e764, 0x00e780,
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@ -211,10 +384,12 @@ nouveau_i2c_init(struct drm_device *dev)
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case 0: /* NV04:NV50 */
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port->drive = entry[0];
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port->sense = entry[1];
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port->adapter.algo = &i2c_bit_algo;
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break;
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case 4: /* NV4E */
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port->drive = 0x600800 + entry[1];
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port->sense = port->drive;
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port->adapter.algo = &i2c_bit_algo;
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break;
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case 5: /* NV50- */
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port->drive = entry[0] & 0x0f;
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@ -227,6 +402,7 @@ nouveau_i2c_init(struct drm_device *dev)
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port->drive = 0x00d014 + (port->drive * 0x20);
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port->sense = port->drive;
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}
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port->adapter.algo = &i2c_bit_algo;
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break;
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case 6: /* NV50- DP AUX */
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port->drive = entry[0];
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@ -237,7 +413,7 @@ nouveau_i2c_init(struct drm_device *dev)
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break;
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}
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if (!port->adapter.algo && !port->drive) {
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if (!port->adapter.algo) {
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NV_ERROR(dev, "I2C%d: type %d index %x/%x unknown\n",
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i, port->type, port->drive, port->sense);
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kfree(port);
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@ -253,26 +429,7 @@ nouveau_i2c_init(struct drm_device *dev)
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port->dcb = ROM32(entry[0]);
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i2c_set_adapdata(&port->adapter, i2c);
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if (port->adapter.algo != &nouveau_dp_i2c_algo) {
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port->adapter.algo_data = &port->bit;
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port->bit.udelay = 40;
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port->bit.timeout = usecs_to_jiffies(5000);
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port->bit.data = port;
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port->bit.setsda = i2c_drive_sda;
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port->bit.setscl = i2c_drive_scl;
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port->bit.getsda = i2c_sense_sda;
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port->bit.getscl = i2c_sense_scl;
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i2c_drive_scl(port, 0);
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i2c_drive_sda(port, 1);
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i2c_drive_scl(port, 1);
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ret = i2c_bit_add_bus(&port->adapter);
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} else {
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port->adapter.algo = &nouveau_dp_i2c_algo;
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ret = i2c_add_adapter(&port->adapter);
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}
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ret = i2c_add_adapter(&port->adapter);
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if (ret) {
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NV_ERROR(dev, "I2C%d: failed register: %d\n", i, ret);
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kfree(port);
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@ -34,7 +34,6 @@
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struct nouveau_i2c_chan {
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struct i2c_adapter adapter;
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struct drm_device *dev;
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struct i2c_algo_bit_data bit;
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struct list_head head;
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u8 index;
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u8 type;
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