summaryrefslogtreecommitdiffstats
path: root/drivers/gpu/drm/nouveau/nvkm/subdev/i2c/bit.c
diff options
context:
space:
mode:
authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
commit2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch)
tree848558de17fb3008cdf4d861b01ac7781903ce39 /drivers/gpu/drm/nouveau/nvkm/subdev/i2c/bit.c
parentInitial commit. (diff)
downloadlinux-upstream.tar.xz
linux-upstream.zip
Adding upstream version 6.1.76.upstream/6.1.76upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'drivers/gpu/drm/nouveau/nvkm/subdev/i2c/bit.c')
-rw-r--r--drivers/gpu/drm/nouveau/nvkm/subdev/i2c/bit.c216
1 files changed, 216 insertions, 0 deletions
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/i2c/bit.c b/drivers/gpu/drm/nouveau/nvkm/subdev/i2c/bit.c
new file mode 100644
index 000000000..cdce11bba
--- /dev/null
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/i2c/bit.c
@@ -0,0 +1,216 @@
+/*
+ * Copyright 2012 Red Hat Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial busions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * Authors: Ben Skeggs
+ */
+#include "bus.h"
+
+#ifdef CONFIG_NOUVEAU_I2C_INTERNAL
+#define T_TIMEOUT 2200000
+#define T_RISEFALL 1000
+#define T_HOLD 5000
+
+static inline void
+nvkm_i2c_drive_scl(struct nvkm_i2c_bus *bus, int state)
+{
+ bus->func->drive_scl(bus, state);
+}
+
+static inline void
+nvkm_i2c_drive_sda(struct nvkm_i2c_bus *bus, int state)
+{
+ bus->func->drive_sda(bus, state);
+}
+
+static inline int
+nvkm_i2c_sense_scl(struct nvkm_i2c_bus *bus)
+{
+ return bus->func->sense_scl(bus);
+}
+
+static inline int
+nvkm_i2c_sense_sda(struct nvkm_i2c_bus *bus)
+{
+ return bus->func->sense_sda(bus);
+}
+
+static void
+nvkm_i2c_delay(struct nvkm_i2c_bus *bus, u32 nsec)
+{
+ udelay((nsec + 500) / 1000);
+}
+
+static bool
+nvkm_i2c_raise_scl(struct nvkm_i2c_bus *bus)
+{
+ u32 timeout = T_TIMEOUT / T_RISEFALL;
+
+ nvkm_i2c_drive_scl(bus, 1);
+ do {
+ nvkm_i2c_delay(bus, T_RISEFALL);
+ } while (!nvkm_i2c_sense_scl(bus) && --timeout);
+
+ return timeout != 0;
+}
+
+static int
+i2c_start(struct nvkm_i2c_bus *bus)
+{
+ int ret = 0;
+
+ if (!nvkm_i2c_sense_scl(bus) ||
+ !nvkm_i2c_sense_sda(bus)) {
+ nvkm_i2c_drive_scl(bus, 0);
+ nvkm_i2c_drive_sda(bus, 1);
+ if (!nvkm_i2c_raise_scl(bus))
+ ret = -EBUSY;
+ }
+
+ nvkm_i2c_drive_sda(bus, 0);
+ nvkm_i2c_delay(bus, T_HOLD);
+ nvkm_i2c_drive_scl(bus, 0);
+ nvkm_i2c_delay(bus, T_HOLD);
+ return ret;
+}
+
+static void
+i2c_stop(struct nvkm_i2c_bus *bus)
+{
+ nvkm_i2c_drive_scl(bus, 0);
+ nvkm_i2c_drive_sda(bus, 0);
+ nvkm_i2c_delay(bus, T_RISEFALL);
+
+ nvkm_i2c_drive_scl(bus, 1);
+ nvkm_i2c_delay(bus, T_HOLD);
+ nvkm_i2c_drive_sda(bus, 1);
+ nvkm_i2c_delay(bus, T_HOLD);
+}
+
+static int
+i2c_bitw(struct nvkm_i2c_bus *bus, int sda)
+{
+ nvkm_i2c_drive_sda(bus, sda);
+ nvkm_i2c_delay(bus, T_RISEFALL);
+
+ if (!nvkm_i2c_raise_scl(bus))
+ return -ETIMEDOUT;
+ nvkm_i2c_delay(bus, T_HOLD);
+
+ nvkm_i2c_drive_scl(bus, 0);
+ nvkm_i2c_delay(bus, T_HOLD);
+ return 0;
+}
+
+static int
+i2c_bitr(struct nvkm_i2c_bus *bus)
+{
+ int sda;
+
+ nvkm_i2c_drive_sda(bus, 1);
+ nvkm_i2c_delay(bus, T_RISEFALL);
+
+ if (!nvkm_i2c_raise_scl(bus))
+ return -ETIMEDOUT;
+ nvkm_i2c_delay(bus, T_HOLD);
+
+ sda = nvkm_i2c_sense_sda(bus);
+
+ nvkm_i2c_drive_scl(bus, 0);
+ nvkm_i2c_delay(bus, T_HOLD);
+ return sda;
+}
+
+static int
+nvkm_i2c_get_byte(struct nvkm_i2c_bus *bus, u8 *byte, bool last)
+{
+ int i, bit;
+
+ *byte = 0;
+ for (i = 7; i >= 0; i--) {
+ bit = i2c_bitr(bus);
+ if (bit < 0)
+ return bit;
+ *byte |= bit << i;
+ }
+
+ return i2c_bitw(bus, last ? 1 : 0);
+}
+
+static int
+nvkm_i2c_put_byte(struct nvkm_i2c_bus *bus, u8 byte)
+{
+ int i, ret;
+ for (i = 7; i >= 0; i--) {
+ ret = i2c_bitw(bus, !!(byte & (1 << i)));
+ if (ret < 0)
+ return ret;
+ }
+
+ ret = i2c_bitr(bus);
+ if (ret == 1) /* nack */
+ ret = -EIO;
+ return ret;
+}
+
+static int
+i2c_addr(struct nvkm_i2c_bus *bus, struct i2c_msg *msg)
+{
+ u32 addr = msg->addr << 1;
+ if (msg->flags & I2C_M_RD)
+ addr |= 1;
+ return nvkm_i2c_put_byte(bus, addr);
+}
+
+int
+nvkm_i2c_bit_xfer(struct nvkm_i2c_bus *bus, struct i2c_msg *msgs, int num)
+{
+ struct i2c_msg *msg = msgs;
+ int ret = 0, mcnt = num;
+
+ while (!ret && mcnt--) {
+ u8 remaining = msg->len;
+ u8 *ptr = msg->buf;
+
+ ret = i2c_start(bus);
+ if (ret == 0)
+ ret = i2c_addr(bus, msg);
+
+ if (msg->flags & I2C_M_RD) {
+ while (!ret && remaining--)
+ ret = nvkm_i2c_get_byte(bus, ptr++, !remaining);
+ } else {
+ while (!ret && remaining--)
+ ret = nvkm_i2c_put_byte(bus, *ptr++);
+ }
+
+ msg++;
+ }
+
+ i2c_stop(bus);
+ return (ret < 0) ? ret : num;
+}
+#else
+int
+nvkm_i2c_bit_xfer(struct nvkm_i2c_bus *bus, struct i2c_msg *msgs, int num)
+{
+ return -ENODEV;
+}
+#endif