[v4,2/2] i2c: mux: pca954x: support property idle-state
diff mbox series

Message ID 20191021080048.47189-2-biwen.li@nxp.com
State Superseded
Headers show
Series
  • [v4,1/2] dt-bindings: i2c: support property idle-state
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Commit Message

Biwen Li Oct. 21, 2019, 8 a.m. UTC
This supports property idle-state

Signed-off-by: Biwen Li <biwen.li@nxp.com>
---
Change in v4:
	- rename function
	  pca954x_calculate_chan -> pca954x_regval

Change in v3:
	- update subject and description
	- add a helper function pca954x_calculate_chan()

Change in v2:
	- update subject and description
	- add property idle-state

 drivers/i2c/muxes/i2c-mux-pca954x.c | 59 ++++++++++++++++++-----------
 1 file changed, 36 insertions(+), 23 deletions(-)

Comments

Peter Rosin Oct. 21, 2019, 1:20 p.m. UTC | #1
On 2019-10-21 10:00, Biwen Li wrote:
> This supports property idle-state
> 

You should expand this a little bit to explain that idle-state, if present,
overrides i2c-mux-idle-disconnect. You could also mention your use case
where you need to avoid disconnects on probe/resume.

> Signed-off-by: Biwen Li <biwen.li@nxp.com>
> ---
> Change in v4:
> 	- rename function
> 	  pca954x_calculate_chan -> pca954x_regval
> 
> Change in v3:
> 	- update subject and description
> 	- add a helper function pca954x_calculate_chan()
> 
> Change in v2:
> 	- update subject and description
> 	- add property idle-state
> 
>  drivers/i2c/muxes/i2c-mux-pca954x.c | 59 ++++++++++++++++++-----------
>  1 file changed, 36 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
> index 923aa3a5a3dc..e566c4cd8ba5 100644
> --- a/drivers/i2c/muxes/i2c-mux-pca954x.c
> +++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
> @@ -86,7 +86,7 @@ struct pca954x {
>  
>  	u8 last_chan;		/* last register value */
>  	/* MUX_IDLE_AS_IS, MUX_IDLE_DISCONNECT or >= 0 for channel */
> -	s8 idle_state;
> +	s32 idle_state;
>  
>  	struct i2c_client *client;
>  
> @@ -229,20 +229,23 @@ static int pca954x_reg_write(struct i2c_adapter *adap,
>  				I2C_SMBUS_BYTE, &dummy);
>  }
>  
> +static u8 pca954x_regval(struct pca954x *data, u8 chan)
> +{
> +	/* we make switches look like muxes, not sure how to be smarter */

I know you are just moving the comment around, but please fix the sentence
to start with a capital letter and end with a period. Sorry I didn't
catch this in v3.

> +	if (data->chip->muxtype == pca954x_ismux)
> +		return chan | data->chip->enable;
> +	else
> +		return 1 << chan;
> +}
> +
>  static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
>  {
>  	struct pca954x *data = i2c_mux_priv(muxc);
>  	struct i2c_client *client = data->client;
> -	const struct chip_desc *chip = data->chip;
>  	u8 regval;
>  	int ret = 0;
>  
> -	/* we make switches look like muxes, not sure how to be smarter */
> -	if (chip->muxtype == pca954x_ismux)
> -		regval = chan | chip->enable;
> -	else
> -		regval = 1 << chan;
> -
> +	regval = pca954x_regval(data, (u8)(chan & 0xff));

Both a mask and a cast to do what the compiler should be doing all by itself?
If you need to kill a warning, or something, please do just one or them. But
personally I prefer the short, sweet and uncluttered:

	regval = pca954x_regval(data, chan);

>  	/* Only select the channel if its different from the last channel */
>  	if (data->last_chan != regval) {
>  		ret = pca954x_reg_write(muxc->parent, client, regval);
> @@ -256,7 +259,7 @@ 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;
> -	s8 idle_state;
> +	s32 idle_state;
>  
>  	idle_state = READ_ONCE(data->idle_state);
>  	if (idle_state >= 0)
> @@ -402,6 +405,17 @@ static void pca954x_cleanup(struct i2c_mux_core *muxc)
>  	i2c_mux_del_adapters(muxc);
>  }
>  
> +static int pca954x_init(struct i2c_client *client, struct pca954x *data)
> +{
> +	if (data->idle_state >= 0) {
> +		data->last_chan = pca954x_regval(data, (u8)(data->idle_state & 0xff));

Dito.

> +	} else {
> +		/* Disconnect multiplexer */
> +		data->last_chan = 0;
> +	}
> +	return i2c_smbus_write_byte(client, data->last_chan);

Here's another thing I missed in the earlier iterations. If i2c_smbus_write_byte
fails here, I think you should set data->last_chan to zero. For the call from
probe it obviously doesn't matter much, but I think the call during resume is
better off with such extra precaution in place.

Cheers,
Peter

> +}
> +
>  /*
>   * I2C init/probing/exit functions
>   */
> @@ -411,7 +425,6 @@ static int pca954x_probe(struct i2c_client *client,
>  	struct i2c_adapter *adap = client->adapter;
>  	struct device *dev = &client->dev;
>  	struct device_node *np = dev->of_node;
> -	bool idle_disconnect_dt;
>  	struct gpio_desc *gpio;
>  	struct i2c_mux_core *muxc;
>  	struct pca954x *data;
> @@ -462,23 +475,24 @@ static int pca954x_probe(struct i2c_client *client,
>  		}
>  	}
>  
> -	/* Write the mux register at addr to verify
> +	data->idle_state = MUX_IDLE_AS_IS;
> +	if (of_property_read_u32(np, "idle-state", &data->idle_state)) {
> +		if (np && of_property_read_bool(np, "i2c-mux-idle-disconnect"))
> +			data->idle_state = MUX_IDLE_DISCONNECT;
> +	}
> +
> +	/*
> +	 * Write the mux register at addr to verify
>  	 * that the mux is in fact present. This also
> -	 * initializes the mux to disconnected state.
> +	 * initializes the mux to a channel
> +	 * or disconnected state.
>  	 */
> -	if (i2c_smbus_write_byte(client, 0) < 0) {
> +	ret = pca954x_init(client, data);
> +	if (ret < 0) {
>  		dev_warn(dev, "probe failed\n");
>  		return -ENODEV;
>  	}
>  
> -	data->last_chan = 0;		   /* force the first selection */
> -	data->idle_state = MUX_IDLE_AS_IS;
> -
> -	idle_disconnect_dt = np &&
> -		of_property_read_bool(np, "i2c-mux-idle-disconnect");
> -	if (idle_disconnect_dt)
> -		data->idle_state = MUX_IDLE_DISCONNECT;
> -
>  	ret = pca954x_irq_setup(muxc);
>  	if (ret)
>  		goto fail_cleanup;
> @@ -531,8 +545,7 @@ static int pca954x_resume(struct device *dev)
>  	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
>  	struct pca954x *data = i2c_mux_priv(muxc);
>  
> -	data->last_chan = 0;
> -	return i2c_smbus_write_byte(client, 0);
> +	return pca954x_init(client, data);
>  }
>  #endif
>  
>
Biwen Li Oct. 22, 2019, 3:51 a.m. UTC | #2
> Caution: EXT Email
> 
> On 2019-10-21 10:00, Biwen Li wrote:
> > This supports property idle-state
> >
> 
> You should expand this a little bit to explain that idle-state, if present, overrides
> i2c-mux-idle-disconnect. You could also mention your use case where you need
> to avoid disconnects on probe/resume.
Okay, got it. I will add some information in v5.
> 
> > Signed-off-by: Biwen Li <biwen.li@nxp.com>
> > ---
> > Change in v4:
> >       - rename function
> >         pca954x_calculate_chan -> pca954x_regval
> >
> > Change in v3:
> >       - update subject and description
> >       - add a helper function pca954x_calculate_chan()
> >
> > Change in v2:
> >       - update subject and description
> >       - add property idle-state
> >
> >  drivers/i2c/muxes/i2c-mux-pca954x.c | 59
> > ++++++++++++++++++-----------
> >  1 file changed, 36 insertions(+), 23 deletions(-)
> >
> > diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c
> > b/drivers/i2c/muxes/i2c-mux-pca954x.c
> > index 923aa3a5a3dc..e566c4cd8ba5 100644
> > --- a/drivers/i2c/muxes/i2c-mux-pca954x.c
> > +++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
> > @@ -86,7 +86,7 @@ struct pca954x {
> >
> >       u8 last_chan;           /* last register value */
> >       /* MUX_IDLE_AS_IS, MUX_IDLE_DISCONNECT or >= 0 for channel */
> > -     s8 idle_state;
> > +     s32 idle_state;
> >
> >       struct i2c_client *client;
> >
> > @@ -229,20 +229,23 @@ static int pca954x_reg_write(struct i2c_adapter
> *adap,
> >                               I2C_SMBUS_BYTE, &dummy);  }
> >
> > +static u8 pca954x_regval(struct pca954x *data, u8 chan) {
> > +     /* we make switches look like muxes, not sure how to be smarter
> > +*/
> 
> I know you are just moving the comment around, but please fix the sentence to
> start with a capital letter and end with a period. Sorry I didn't catch this in v3.
Okay, got it, I will fix it in v5.
> 
> > +     if (data->chip->muxtype == pca954x_ismux)
> > +             return chan | data->chip->enable;
> > +     else
> > +             return 1 << chan;
> > +}
> > +
> >  static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
> > {
> >       struct pca954x *data = i2c_mux_priv(muxc);
> >       struct i2c_client *client = data->client;
> > -     const struct chip_desc *chip = data->chip;
> >       u8 regval;
> >       int ret = 0;
> >
> > -     /* we make switches look like muxes, not sure how to be smarter */
> > -     if (chip->muxtype == pca954x_ismux)
> > -             regval = chan | chip->enable;
> > -     else
> > -             regval = 1 << chan;
> > -
> > +     regval = pca954x_regval(data, (u8)(chan & 0xff));
> 
> Both a mask and a cast to do what the compiler should be doing all by itself?
> If you need to kill a warning, or something, please do just one or them. But
> personally I prefer the short, sweet and uncluttered:
Okay, got it, thanks. I will adjust it in v5.
> 
>         regval = pca954x_regval(data, chan);
> 
> >       /* Only select the channel if its different from the last channel */
> >       if (data->last_chan != regval) {
> >               ret = pca954x_reg_write(muxc->parent, client, regval);
> > @@ -256,7 +259,7 @@ 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;
> > -     s8 idle_state;
> > +     s32 idle_state;
> >
> >       idle_state = READ_ONCE(data->idle_state);
> >       if (idle_state >= 0)
> > @@ -402,6 +405,17 @@ static void pca954x_cleanup(struct i2c_mux_core
> *muxc)
> >       i2c_mux_del_adapters(muxc);
> >  }
> >
> > +static int pca954x_init(struct i2c_client *client, struct pca954x
> > +*data) {
> > +     if (data->idle_state >= 0) {
> > +             data->last_chan = pca954x_regval(data,
> > +(u8)(data->idle_state & 0xff));
> 
> Dito.

Got it, thanks.
> 
> > +     } else {
> > +             /* Disconnect multiplexer */
> > +             data->last_chan = 0;
> > +     }
> > +     return i2c_smbus_write_byte(client, data->last_chan);
> 
> Here's another thing I missed in the earlier iterations. If i2c_smbus_write_byte
> fails here, I think you should set data->last_chan to zero. For the call from probe
> it obviously doesn't matter much, but I think the call during resume is better off
> with such extra precaution in place.
You are right. I will add extra precaution in v5.
> 
> Cheers,
> Peter
> 
> > +}
> > +
> >  /*
> >   * I2C init/probing/exit functions
> >   */
> > @@ -411,7 +425,6 @@ static int pca954x_probe(struct i2c_client *client,
> >       struct i2c_adapter *adap = client->adapter;
> >       struct device *dev = &client->dev;
> >       struct device_node *np = dev->of_node;
> > -     bool idle_disconnect_dt;
> >       struct gpio_desc *gpio;
> >       struct i2c_mux_core *muxc;
> >       struct pca954x *data;
> > @@ -462,23 +475,24 @@ static int pca954x_probe(struct i2c_client *client,
> >               }
> >       }
> >
> > -     /* Write the mux register at addr to verify
> > +     data->idle_state = MUX_IDLE_AS_IS;
> > +     if (of_property_read_u32(np, "idle-state", &data->idle_state)) {
> > +             if (np && of_property_read_bool(np,
> "i2c-mux-idle-disconnect"))
> > +                     data->idle_state = MUX_IDLE_DISCONNECT;
> > +     }
> > +
> > +     /*
> > +      * Write the mux register at addr to verify
> >        * that the mux is in fact present. This also
> > -      * initializes the mux to disconnected state.
> > +      * initializes the mux to a channel
> > +      * or disconnected state.
> >        */
> > -     if (i2c_smbus_write_byte(client, 0) < 0) {
> > +     ret = pca954x_init(client, data);
> > +     if (ret < 0) {
> >               dev_warn(dev, "probe failed\n");
> >               return -ENODEV;
> >       }
> >
> > -     data->last_chan = 0;               /* force the first selection */
> > -     data->idle_state = MUX_IDLE_AS_IS;
> > -
> > -     idle_disconnect_dt = np &&
> > -             of_property_read_bool(np, "i2c-mux-idle-disconnect");
> > -     if (idle_disconnect_dt)
> > -             data->idle_state = MUX_IDLE_DISCONNECT;
> > -
> >       ret = pca954x_irq_setup(muxc);
> >       if (ret)
> >               goto fail_cleanup;
> > @@ -531,8 +545,7 @@ static int pca954x_resume(struct device *dev)
> >       struct i2c_mux_core *muxc = i2c_get_clientdata(client);
> >       struct pca954x *data = i2c_mux_priv(muxc);
> >
> > -     data->last_chan = 0;
> > -     return i2c_smbus_write_byte(client, 0);
> > +     return pca954x_init(client, data);
> >  }
> >  #endif
> >
> >

Patch
diff mbox series

diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
index 923aa3a5a3dc..e566c4cd8ba5 100644
--- a/drivers/i2c/muxes/i2c-mux-pca954x.c
+++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
@@ -86,7 +86,7 @@  struct pca954x {
 
 	u8 last_chan;		/* last register value */
 	/* MUX_IDLE_AS_IS, MUX_IDLE_DISCONNECT or >= 0 for channel */
-	s8 idle_state;
+	s32 idle_state;
 
 	struct i2c_client *client;
 
@@ -229,20 +229,23 @@  static int pca954x_reg_write(struct i2c_adapter *adap,
 				I2C_SMBUS_BYTE, &dummy);
 }
 
+static u8 pca954x_regval(struct pca954x *data, u8 chan)
+{
+	/* we make switches look like muxes, not sure how to be smarter */
+	if (data->chip->muxtype == pca954x_ismux)
+		return chan | data->chip->enable;
+	else
+		return 1 << chan;
+}
+
 static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
 {
 	struct pca954x *data = i2c_mux_priv(muxc);
 	struct i2c_client *client = data->client;
-	const struct chip_desc *chip = data->chip;
 	u8 regval;
 	int ret = 0;
 
-	/* we make switches look like muxes, not sure how to be smarter */
-	if (chip->muxtype == pca954x_ismux)
-		regval = chan | chip->enable;
-	else
-		regval = 1 << chan;
-
+	regval = pca954x_regval(data, (u8)(chan & 0xff));
 	/* Only select the channel if its different from the last channel */
 	if (data->last_chan != regval) {
 		ret = pca954x_reg_write(muxc->parent, client, regval);
@@ -256,7 +259,7 @@  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;
-	s8 idle_state;
+	s32 idle_state;
 
 	idle_state = READ_ONCE(data->idle_state);
 	if (idle_state >= 0)
@@ -402,6 +405,17 @@  static void pca954x_cleanup(struct i2c_mux_core *muxc)
 	i2c_mux_del_adapters(muxc);
 }
 
+static int pca954x_init(struct i2c_client *client, struct pca954x *data)
+{
+	if (data->idle_state >= 0) {
+		data->last_chan = pca954x_regval(data, (u8)(data->idle_state & 0xff));
+	} else {
+		/* Disconnect multiplexer */
+		data->last_chan = 0;
+	}
+	return i2c_smbus_write_byte(client, data->last_chan);
+}
+
 /*
  * I2C init/probing/exit functions
  */
@@ -411,7 +425,6 @@  static int pca954x_probe(struct i2c_client *client,
 	struct i2c_adapter *adap = client->adapter;
 	struct device *dev = &client->dev;
 	struct device_node *np = dev->of_node;
-	bool idle_disconnect_dt;
 	struct gpio_desc *gpio;
 	struct i2c_mux_core *muxc;
 	struct pca954x *data;
@@ -462,23 +475,24 @@  static int pca954x_probe(struct i2c_client *client,
 		}
 	}
 
-	/* Write the mux register at addr to verify
+	data->idle_state = MUX_IDLE_AS_IS;
+	if (of_property_read_u32(np, "idle-state", &data->idle_state)) {
+		if (np && of_property_read_bool(np, "i2c-mux-idle-disconnect"))
+			data->idle_state = MUX_IDLE_DISCONNECT;
+	}
+
+	/*
+	 * Write the mux register at addr to verify
 	 * that the mux is in fact present. This also
-	 * initializes the mux to disconnected state.
+	 * initializes the mux to a channel
+	 * or disconnected state.
 	 */
-	if (i2c_smbus_write_byte(client, 0) < 0) {
+	ret = pca954x_init(client, data);
+	if (ret < 0) {
 		dev_warn(dev, "probe failed\n");
 		return -ENODEV;
 	}
 
-	data->last_chan = 0;		   /* force the first selection */
-	data->idle_state = MUX_IDLE_AS_IS;
-
-	idle_disconnect_dt = np &&
-		of_property_read_bool(np, "i2c-mux-idle-disconnect");
-	if (idle_disconnect_dt)
-		data->idle_state = MUX_IDLE_DISCONNECT;
-
 	ret = pca954x_irq_setup(muxc);
 	if (ret)
 		goto fail_cleanup;
@@ -531,8 +545,7 @@  static int pca954x_resume(struct device *dev)
 	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
 	struct pca954x *data = i2c_mux_priv(muxc);
 
-	data->last_chan = 0;
-	return i2c_smbus_write_byte(client, 0);
+	return pca954x_init(client, data);
 }
 #endif