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i2c: meson: add some comments

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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>
This commit is contained in:
Beniamino Galvani 2017-11-26 17:40:57 +01:00 committed by Heiko Schocher
parent 989bb924c4
commit 50a69095cb
1 changed files with 19 additions and 6 deletions
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25
drivers/i2c/meson_i2c.c
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@ -44,12 +44,12 @@ struct i2c_regs {
struct meson_i2c { struct meson_i2c {
struct i2c_regs *regs; struct i2c_regs *regs;
struct i2c_msg *msg; struct i2c_msg *msg; /* Current I2C message */
bool last; bool last; /* Whether the message is the last */
uint count; uint count; /* Number of bytes in the current transfer */
uint pos; uint pos; /* Position of current transfer in message */
u32 tokens[2]; u32 tokens[2]; /* Sequence of tokens to be written */
uint num_tokens; uint num_tokens; /* Number of tokens to be written */
}; };
static void meson_i2c_reset_tokens(struct meson_i2c *i2c) static void meson_i2c_reset_tokens(struct meson_i2c *i2c)
@ -69,6 +69,10 @@ static void meson_i2c_add_token(struct meson_i2c *i2c, int token)
i2c->num_tokens++; 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) static void meson_i2c_get_data(struct meson_i2c *i2c, u8 *buf, int len)
{ {
u32 rdata0, rdata1; u32 rdata0, rdata1;
@ -86,6 +90,10 @@ static void meson_i2c_get_data(struct meson_i2c *i2c, u8 *buf, int len)
*buf++ = (rdata1 >> (i - 4) * 8) & 0xff; *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) static void meson_i2c_put_data(struct meson_i2c *i2c, u8 *buf, int len)
{ {
u32 wdata0 = 0, wdata1 = 0; u32 wdata0 = 0, wdata1 = 0;
@ -103,6 +111,11 @@ static void meson_i2c_put_data(struct meson_i2c *i2c, u8 *buf, int len)
debug("meson i2c: write data %08x %08x len %d\n", wdata0, wdata1, len); 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) static void meson_i2c_prepare_xfer(struct meson_i2c *i2c)
{ {
bool write = !(i2c->msg->flags & I2C_M_RD); bool write = !(i2c->msg->flags & I2C_M_RD);