Re: [PATCH] nvmem: qfprom: increase id to support multiple devices

[Srinivas Kandagatla <srinivas.kandagatla@linaro.org>]

Hi Shawn,
Thankyou for the patch!


On 29/06/2020 14:32, Shawn Guo wrote:
> There could be multiple qfprom devices on some SoCs.  For example, on
> MSM8939, qfprom@58000 holds efuse bits for Core Power Reduction (CPR),
> and qfprom@5c000 holds bits for TSENS.  Registering multiple nvmem
> devices with the same id results in the following failure on the second
> device.
> 
> [    1.682731] sysfs: cannot create duplicate filename '/bus/nvmem/devices/qfprom0'
> [    1.685889] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.19.107-00567-g11c887ce2838-dirty #334
> [    1.693191] Hardware name: Square, Inc. T2 Devkit (DT)
> [    1.701610] Call trace:
> [    1.706673]  dump_backtrace+0x0/0x158
> [    1.708987]  show_stack+0x14/0x20
> [    1.712810]  dump_stack+0x98/0xbc
> [    1.716114]  sysfs_warn_dup+0x60/0x78
> [    1.719401]  sysfs_do_create_link_sd.isra.0+0xdc/0xe8
> [    1.723047]  sysfs_create_link+0x20/0x40
> [    1.728088]  bus_add_device+0x68/0x130
> [    1.732083]  device_add+0x3f8/0x628
> [    1.735639]  nvmem_register.part.4+0x150/0x348
> [    1.739018]  devm_nvmem_register+0x4c/0xa8
> [    1.743532]  qfprom_probe+0x94/0xb8
> [    1.747615]  platform_drv_probe+0x50/0xa0
> [    1.750998]  really_probe+0x1b8/0x298
> [    1.755164]  driver_probe_device+0x58/0x100
> [    1.758810]  __driver_attach+0xe0/0xe8
> [    1.762802]  bus_for_each_dev+0x74/0xc8
> [    1.766622]  driver_attach+0x20/0x28
> [    1.770354]  bus_add_driver+0x1ac/0x218
> [    1.774175]  driver_register+0x60/0x110
> [    1.777734]  __platform_driver_register+0x40/0x48
> [    1.781570]  qfprom_driver_init+0x18/0x20
> [    1.786416]  do_one_initcall+0x5c/0x178
> [    1.790418]  kernel_init_freeable+0x198/0x244
> [    1.794062]  kernel_init+0x10/0x108
> [    1.798567]  ret_from_fork+0x10/0x18
> [    1.802084] qcom,qfprom: probe of 5c000.qfprom failed with error -17
> 


> Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
> ---
>   drivers/nvmem/qfprom.c | 2 ++
>   1 file changed, 2 insertions(+)

TBH, this functionality need to go into core driver which already has 
IDR to allocated ID's for nvmem providers.

Can you try this patch:

---------------------------->cut<---------------------------------diff 
--git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 927eb5f6003f..aa87bd6415ab 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -629,12 +629,18 @@ struct nvmem_device *nvmem_register(const struct 
nvmem_config *config)
         if (!config->no_of_node)
                 nvmem->dev.of_node = config->dev->of_node;

-       if (config->id == -1 && config->name) {
+       switch (config->id) {
+       case NVMEM_DEVID_NONE:
                 dev_set_name(&nvmem->dev, "%s", config->name);
-       } else {
+               break;
+       case NVMEM_DEVID_AUTO:
+               dev_set_name(&nvmem->dev, "%s%d", config->name, nvmem->id);
+               break;
+       default:
                 dev_set_name(&nvmem->dev, "%s%d",
                              config->name ? : "nvmem",
                              config->name ? config->id : nvmem->id);
+               break;
         }

         nvmem->read_only = device_property_present(config->dev, 
"read-only") ||
diff --git a/drivers/nvmem/qfprom.c b/drivers/nvmem/qfprom.c
index 8a91717600be..8b425f8d847d 100644
--- a/drivers/nvmem/qfprom.c
+++ b/drivers/nvmem/qfprom.c
@@ -31,6 +31,7 @@ static struct nvmem_config econfig = {
         .name = "qfprom",
         .stride = 1,
         .word_size = 1,
+       .id = NVMEM_DEVID_AUTO,
         .reg_read = qfprom_reg_read,
  };

diff --git a/include/linux/nvmem-provider.h b/include/linux/nvmem-provider.h
index 6d6f8e5d24c9..06409a6c40bc 100644
--- a/include/linux/nvmem-provider.h
+++ b/include/linux/nvmem-provider.h
@@ -27,6 +27,9 @@ enum nvmem_type {
         NVMEM_TYPE_BATTERY_BACKED,
  };

+#define NVMEM_DEVID_NONE       (-1)
+#define NVMEM_DEVID_AUTO       (-2)
+
  /**
   * struct nvmem_config - NVMEM device configuration
   *
---------------------------->cut<---------------------------------

Thanks,
srini
> 
> diff --git a/drivers/nvmem/qfprom.c b/drivers/nvmem/qfprom.c
> index 8a91717600be..ceb837e861d8 100644
> --- a/drivers/nvmem/qfprom.c
> +++ b/drivers/nvmem/qfprom.c
> @@ -40,6 +40,7 @@ static int qfprom_probe(struct platform_device *pdev)
>   	struct resource *res;
>   	struct nvmem_device *nvmem;
>   	struct qfprom_priv *priv;
> +	static int id;
>   
>   	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>   	if (!priv)
> @@ -52,6 +53,7 @@ static int qfprom_probe(struct platform_device *pdev)
>   
>   	econfig.size = resource_size(res);
>   	econfig.dev = dev;
> +	econfig.id = id++;
>   	econfig.priv = priv;
>   
>   	nvmem = devm_nvmem_register(dev, &econfig);
>