Re: [PATCH v2 1/9] hw/i2c/pca954x: Add method to get channels

[Corey Minyard]

On Tue, Jul 05, 2022 at 12:13:52PM -0700, Peter Delevoryas wrote:
> I added this helper in the Aspeed machine file a while ago to help
> initialize fuji-bmc i2c devices. This moves it to the official pca954x
> file so that other files can use it.
> 
> This does something very similar to pca954x_i2c_get_bus, but I think
> this is useful when you have a very complicated dts with a lot of
> switches, like the fuji dts.
> 
> This convenience method lets you write code that produces a flat array
> of I2C buses that matches the naming in the dts. After that you can just
> add individual sensors using the flat array of I2C buses.

This is an improvment, I think.  But it really needs to be two patches,
one with the I2C portion, and one with the aspeed portion.

Also, the name is a little misleading, you might want to name it 
pca954x_i2c_create_get_channels

-corey

> 
> See fuji_bmc_i2c_init to understand this point further.
> 
> The fuji dts is here for reference:
> 
> https://github.com/torvalds/linux/blob/40cb6373b46/arch/arm/boot/dts/aspeed-bmc-facebook-fuji.dts
> 
> Signed-off-by: Peter Delevoryas <peter@pjd.dev>
> ---
>  hw/arm/aspeed.c                  | 29 +++++++++--------------------
>  hw/i2c/i2c_mux_pca954x.c         | 10 ++++++++++
>  include/hw/i2c/i2c_mux_pca954x.h | 13 +++++++++++++
>  3 files changed, 32 insertions(+), 20 deletions(-)
> 
> diff --git a/hw/arm/aspeed.c b/hw/arm/aspeed.c
> index 6fe9b13548..bee8a748ec 100644
> --- a/hw/arm/aspeed.c
> +++ b/hw/arm/aspeed.c
> @@ -793,15 +793,6 @@ static void rainier_bmc_i2c_init(AspeedMachineState *bmc)
>      create_pca9552(soc, 15, 0x60);
>  }
>  
> -static void get_pca9548_channels(I2CBus *bus, uint8_t mux_addr,
> -                                 I2CBus **channels)
> -{
> -    I2CSlave *mux = i2c_slave_create_simple(bus, "pca9548", mux_addr);
> -    for (int i = 0; i < 8; i++) {
> -        channels[i] = pca954x_i2c_get_bus(mux, i);
> -    }
> -}
> -
>  #define TYPE_LM75 TYPE_TMP105
>  #define TYPE_TMP75 TYPE_TMP105
>  #define TYPE_TMP422 "tmp422"
> @@ -814,20 +805,18 @@ static void fuji_bmc_i2c_init(AspeedMachineState *bmc)
>      for (int i = 0; i < 16; i++) {
>          i2c[i] = aspeed_i2c_get_bus(&soc->i2c, i);
>      }
> -    I2CBus *i2c180 = i2c[2];
> -    I2CBus *i2c480 = i2c[8];
> -    I2CBus *i2c600 = i2c[11];
>  
> -    get_pca9548_channels(i2c180, 0x70, &i2c[16]);
> -    get_pca9548_channels(i2c480, 0x70, &i2c[24]);
> +    pca954x_i2c_get_channels(i2c[2], 0x70, "pca9548", &i2c[16]);
> +    pca954x_i2c_get_channels(i2c[8], 0x70, "pca9548", &i2c[24]);
>      /* NOTE: The device tree skips [32, 40) in the alias numbering */
> -    get_pca9548_channels(i2c600, 0x77, &i2c[40]);
> -    get_pca9548_channels(i2c[24], 0x71, &i2c[48]);
> -    get_pca9548_channels(i2c[25], 0x72, &i2c[56]);
> -    get_pca9548_channels(i2c[26], 0x76, &i2c[64]);
> -    get_pca9548_channels(i2c[27], 0x76, &i2c[72]);
> +    pca954x_i2c_get_channels(i2c[11], 0x77, "pca9548", &i2c[40]);
> +    pca954x_i2c_get_channels(i2c[24], 0x71, "pca9548", &i2c[48]);
> +    pca954x_i2c_get_channels(i2c[25], 0x72, "pca9548", &i2c[56]);
> +    pca954x_i2c_get_channels(i2c[26], 0x76, "pca9548", &i2c[64]);
> +    pca954x_i2c_get_channels(i2c[27], 0x76, "pca9548", &i2c[72]);
>      for (int i = 0; i < 8; i++) {
> -        get_pca9548_channels(i2c[40 + i], 0x76, &i2c[80 + i * 8]);
> +        pca954x_i2c_get_channels(i2c[40 + i], 0x76, "pca9548",
> +                                 &i2c[80 + i * 8]);
>      }
>  
>      i2c_slave_create_simple(i2c[17], TYPE_LM75, 0x4c);
> diff --git a/hw/i2c/i2c_mux_pca954x.c b/hw/i2c/i2c_mux_pca954x.c
> index 3945de795c..6b07804546 100644
> --- a/hw/i2c/i2c_mux_pca954x.c
> +++ b/hw/i2c/i2c_mux_pca954x.c
> @@ -169,6 +169,16 @@ I2CBus *pca954x_i2c_get_bus(I2CSlave *mux, uint8_t 
> channel)
>      return pca954x->bus[channel];
>  }
>  
> +void pca954x_i2c_get_channels(I2CBus *bus, uint8_t address,
> +                              const char *type_name, I2CBus **channels)
> +{
> +    I2CSlave *mux = i2c_slave_create_simple(bus, type_name, address);
> +    Pca954xClass *pc = PCA954X_GET_CLASS(mux);
> +    Pca954xState *pca954x = PCA954X(mux);
> +
> +    memcpy(channels, pca954x->bus, pc->nchans * sizeof(channels[0]));
> +}
> +
>  static void pca9546_class_init(ObjectClass *klass, void *data)
>  {
>      Pca954xClass *s = PCA954X_CLASS(klass);
> diff --git a/include/hw/i2c/i2c_mux_pca954x.h 
> b/include/hw/i2c/i2c_mux_pca954x.h
> index 3dd25ec983..3a676a30a9 100644
> --- a/include/hw/i2c/i2c_mux_pca954x.h
> +++ b/include/hw/i2c/i2c_mux_pca954x.h
> @@ -16,4 +16,17 @@
>   */
>  I2CBus *pca954x_i2c_get_bus(I2CSlave *mux, uint8_t channel);
>  
> +/**
> + * Creates an i2c mux and retrieves all of the channels associated with it.
> + *
> + * @bus: the i2c bus where the i2c mux resides.
> + * @address: the address of the i2c mux on the aforementioned i2c bus.
> + * @type_name: name of the i2c mux type to create.
> + * @channels: an output parameter specifying where to return the channels.
> + *
> + * Returns: None
> + */
> +void pca954x_i2c_get_channels(I2CBus *bus, uint8_t address,
> +                              const char *type_name, I2CBus **channels);
> +
>  #endif
> -- 
> 2.37.0
> 
>