i2c: meson: add some comments
Add some comment describing the purpose of struct members and
functions.
Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heiko Schocher <hs@denx.de>
diff --git a/drivers/i2c/meson_i2c.c b/drivers/i2c/meson_i2c.c
index 2f39214..4f37d2f 100644
--- a/drivers/i2c/meson_i2c.c
+++ b/drivers/i2c/meson_i2c.c
@@ -44,12 +44,12 @@
struct meson_i2c {
struct i2c_regs *regs;
- struct i2c_msg *msg;
- bool last;
- uint count;
- uint pos;
- u32 tokens[2];
- uint num_tokens;
+ struct i2c_msg *msg; /* Current I2C message */
+ bool last; /* Whether the message is the last */
+ uint count; /* Number of bytes in the current transfer */
+ uint pos; /* Position of current transfer in message */
+ u32 tokens[2]; /* Sequence of tokens to be written */
+ uint num_tokens; /* Number of tokens to be written */
};
static void meson_i2c_reset_tokens(struct meson_i2c *i2c)
@@ -69,6 +69,10 @@
i2c->num_tokens++;
}
+/*
+ * Retrieve data for the current transfer (which can be at most 8
+ * bytes) from the device internal buffer.
+ */
static void meson_i2c_get_data(struct meson_i2c *i2c, u8 *buf, int len)
{
u32 rdata0, rdata1;
@@ -86,6 +90,10 @@
*buf++ = (rdata1 >> (i - 4) * 8) & 0xff;
}
+/*
+ * Write data for the current transfer (which can be at most 8 bytes)
+ * to the device internal buffer.
+ */
static void meson_i2c_put_data(struct meson_i2c *i2c, u8 *buf, int len)
{
u32 wdata0 = 0, wdata1 = 0;
@@ -103,6 +111,11 @@
debug("meson i2c: write data %08x %08x len %d\n", wdata0, wdata1, len);
}
+/*
+ * Prepare the next transfer: pick the next 8 bytes in the remaining
+ * part of message and write tokens and data (if needed) to the
+ * device.
+ */
static void meson_i2c_prepare_xfer(struct meson_i2c *i2c)
{
bool write = !(i2c->msg->flags & I2C_M_RD);