diff options
| author | Wojciech Siudy <wojciech.siudy@nokia.com> | 2025-06-03 14:47:21 +0200 |
|---|---|---|
| committer | Wolfram Sang <wsa+renesas@sang-engineering.com> | 2025-08-11 20:10:09 +0200 |
| commit | 94c29677640312fcfab261bddc1006bc43efe4ba (patch) | |
| tree | f079fd4b59d2dfb22a03d2e1c1c3d48c9e439179 /drivers/i2c | |
| parent | 690de2902dca98aec96de004428c020ca902f047 (diff) | |
| download | net-94c29677640312fcfab261bddc1006bc43efe4ba.tar.gz | |
i2c: muxes: pca954x: Reset if (de)select fails
If the channel selection or deselection times out, it indicates
a failure in the mux's I2C subsystem. Without sending a reset pulse,
a power-on-reset of the entire device would be required to restore
communication.
The datasheet specifies a minimum hold time of 4 ns for the reset
pulse, but due to the path's capacitance and themux having its own
clock, it is recommended to extend this to approximately 1 us.
Since reset controller is used, there is no need to take care of other
devices sharing the same reset line.
Signed-off-by: Wojciech Siudy <wojciech.siudy@nokia.com>
[wsa: removed superfluous prinout, unneeded braces and fixed indent]
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/muxes/i2c-mux-pca954x.c | 34 |
1 files changed, 26 insertions, 8 deletions
diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c index a9ddd548781ccf..75c8d08fa24e56 100644 --- a/drivers/i2c/muxes/i2c-mux-pca954x.c +++ b/drivers/i2c/muxes/i2c-mux-pca954x.c @@ -315,6 +315,25 @@ static u8 pca954x_regval(struct pca954x *data, u8 chan) return 1 << chan; } +static void pca954x_reset_assert(struct pca954x *data) +{ + if (data->reset_cont) + reset_control_assert(data->reset_cont); +} + +static void pca954x_reset_deassert(struct pca954x *data) +{ + if (data->reset_cont) + reset_control_deassert(data->reset_cont); +} + +static void pca954x_reset_mux(struct pca954x *data) +{ + pca954x_reset_assert(data); + udelay(1); + pca954x_reset_deassert(data); +} + static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan) { struct pca954x *data = i2c_mux_priv(muxc); @@ -328,6 +347,8 @@ static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan) ret = pca954x_reg_write(muxc->parent, client, regval); data->last_chan = ret < 0 ? 0 : regval; } + if (ret == -ETIMEDOUT && data->reset_cont) + pca954x_reset_mux(data); return ret; } @@ -337,6 +358,7 @@ static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan) struct pca954x *data = i2c_mux_priv(muxc); struct i2c_client *client = data->client; s32 idle_state; + int ret = 0; idle_state = READ_ONCE(data->idle_state); if (idle_state >= 0) @@ -346,8 +368,10 @@ static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan) if (idle_state == MUX_IDLE_DISCONNECT) { /* Deselect active channel */ data->last_chan = 0; - return pca954x_reg_write(muxc->parent, client, - data->last_chan); + ret = pca954x_reg_write(muxc->parent, client, + data->last_chan); + if (ret == -ETIMEDOUT && data->reset_cont) + pca954x_reset_mux(data); } /* otherwise leave as-is */ @@ -530,12 +554,6 @@ static int pca954x_get_reset(struct device *dev, struct pca954x *data) return 0; } -static void pca954x_reset_deassert(struct pca954x *data) -{ - if (data->reset_cont) - reset_control_deassert(data->reset_cont); -} - /* * I2C init/probing/exit functions */ |