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Subject: Re: [PATCH v3 5/6] hwmon: pmbus: adm1266: read blackbox
To:     alexandru.tachici@analog.com, linux-hwmon@vger.kernel.org,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org
Cc:     robh+dt@kernel.org
References: <20200529130506.73511-1-alexandru.tachici@analog.com>
 <20200529130506.73511-6-alexandru.tachici@analog.com>
From:   Guenter Roeck <linux@roeck-us.net>
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Message-ID: <80800d67-85ae-d6f1-b400-c230296e1eaf@roeck-us.net>
Date:   Fri, 29 May 2020 11:45:08 -0700
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On 5/29/20 6:05 AM, alexandru.tachici@analog.com wrote:
> From: Alexandru Tachici <alexandru.tachici@analog.com>
> 
> Use the nvmem kernel api to expose the black box
> chip functionality to userspace.
> 

This needs to be split into two functions: Add nvmem support, add
debugfs file.

Guenter

> Signed-off-by: Alexandru Tachici <alexandru.tachici@analog.com>
> ---
>  drivers/hwmon/pmbus/adm1266.c | 160 ++++++++++++++++++++++++++++++++++
>  1 file changed, 160 insertions(+)
> 
> diff --git a/drivers/hwmon/pmbus/adm1266.c b/drivers/hwmon/pmbus/adm1266.c
> index 85d6795b79d3..831156004087 100644
> --- a/drivers/hwmon/pmbus/adm1266.c
> +++ b/drivers/hwmon/pmbus/adm1266.c
> @@ -14,14 +14,19 @@
>  #include <linux/init.h>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
> +#include <linux/nvmem-consumer.h>
> +#include <linux/nvmem-provider.h>
>  #include <linux/slab.h>
>  
>  #include "pmbus.h"
>  
> +#define ADM1266_BLACKBOX_CONFIG	0xD3
>  #define ADM1266_PDIO_CONFIG	0xD4
>  #define ADM1266_GO_COMMAND	0xD8
>  #define ADM1266_READ_STATE	0xD9
> +#define ADM1266_READ_BLACKBOX	0xDE
>  #define ADM1266_GPIO_CONFIG	0xE1
> +#define ADM1266_BLACKBOX_INFO	0xE6
>  #define ADM1266_PDIO_STATUS	0xE9
>  #define ADM1266_GPIO_STATUS	0xEA
>  
> @@ -38,12 +43,26 @@
>  #define ADM1266_PDIO_GLITCH_FILT(x)	FIELD_GET(GENMASK(12, 9), x)
>  #define ADM1266_PDIO_OUT_CFG(x)		FIELD_GET(GENMASK(2, 0), x)
>  
> +#define ADM1266_BLACKBOX_OFFSET		0x7F700
> +#define ADM1266_BLACKBOX_SIZE		64
> +
>  struct adm1266_data {
>  	struct pmbus_driver_info info;
>  	struct gpio_chip gc;
>  	const char *gpio_names[ADM1266_GPIO_NR + ADM1266_PDIO_NR];
>  	struct i2c_client *client;
>  	struct dentry *debugfs_dir;
> +	struct nvmem_config nvmem_config;
> +	struct nvmem_device *nvmem;
> +	u8 *dev_mem;
> +};
> +
> +static const struct nvmem_cell_info adm1266_nvmem_cells[] = {
> +	{
> +		.name           = "blackbox",
> +		.offset         = ADM1266_BLACKBOX_OFFSET,
> +		.bytes          = 2048,
> +	},
>  };
>  
>  #if IS_ENABLED(CONFIG_GPIOLIB)
> @@ -261,6 +280,28 @@ static int adm1266_set_go_command_op(void *pdata, u64 val)
>  	return i2c_smbus_write_word_data(data->client, ADM1266_GO_COMMAND, reg);
>  }
>  
> +static int adm1266_blackbox_information_read(struct seq_file *s, void *pdata)
> +{
> +	struct device *dev = s->private;
> +	struct i2c_client *client = to_i2c_client(dev);
> +	u8 read_buf[PMBUS_BLOCK_MAX + 1];
> +	unsigned int latest_id;
> +	int ret;
> +
> +	ret = i2c_smbus_read_block_data(client, ADM1266_BLACKBOX_INFO,
> +					read_buf);
> +	if (ret < 0)
> +		return ret;
> +
> +	seq_puts(s, "BLACKBOX_INFORMATION:\n");
> +	latest_id = read_buf[0] + (read_buf[1] << 8);
> +	seq_printf(s, "Black box ID: %x\n", latest_id);
> +	seq_printf(s, "Logic index: %x\n", read_buf[2]);
> +	seq_printf(s, "Record count: %x\n", read_buf[3]);
> +
> +	return 0;
> +}
> +
>  DEFINE_DEBUGFS_ATTRIBUTE(go_command_fops, NULL, adm1266_set_go_command_op,
>  			 "%llu\n");
>  DEFINE_DEBUGFS_ATTRIBUTE(read_state_fops, adm1266_get_state_op, NULL, "%llu\n");
> @@ -277,6 +318,121 @@ static void adm1266_debug_init(struct adm1266_data *data)
>  				   &go_command_fops);
>  	debugfs_create_file_unsafe("read_state", 0400, root, data,
>  				   &read_state_fops);
> +	debugfs_create_devm_seqfile(&data->client->dev, "blackbox_information",
> +				    root, adm1266_blackbox_information_read);
> +}
> +
> +static int adm1266_nvmem_read_blackbox(struct adm1266_data *data, u8 *buf)
> +{
> +	u8 write_buf[PMBUS_BLOCK_MAX + 1];
> +	u8 read_buf[PMBUS_BLOCK_MAX + 1];
> +	int record_count;
> +	int ret;
> +	int i;
> +
> +	ret = i2c_smbus_read_block_data(data->client, ADM1266_BLACKBOX_INFO,
> +					read_buf);
> +	if (ret < 0)
> +		return ret;
> +
> +	record_count = read_buf[3];
> +
> +	for (i = 0; i < record_count; i++) {
> +		write_buf[0] = i;
> +		ret = pmbus_block_wr(data->client, ADM1266_READ_BLACKBOX, 1,
> +				     write_buf, buf);
> +		if (ret < 0)
> +			return ret;
> +
> +		buf += ADM1266_BLACKBOX_SIZE;
> +	}
> +
> +	return 0;
> +}
> +
> +static bool adm1266_cell_is_accessed(const struct nvmem_cell_info *mem_cell,
> +				     unsigned int offset, size_t bytes)
> +{
> +	unsigned int start_addr = offset;
> +	unsigned int end_addr = offset + bytes;
> +	unsigned int cell_start = mem_cell->offset;
> +	unsigned int cell_end = mem_cell->offset + mem_cell->bytes;
> +
> +	if (start_addr <= cell_end && cell_start <= end_addr)
> +		return true;
> +
> +	return false;
> +}
> +
> +static int adm1266_read_mem_cell(struct adm1266_data *data,
> +				 const struct nvmem_cell_info *mem_cell)
> +{
> +	u8 *mem_offset;
> +	int ret;
> +
> +	switch (mem_cell->offset) {
> +	case ADM1266_BLACKBOX_OFFSET:
> +		mem_offset = data->dev_mem + mem_cell->offset;
> +		ret = adm1266_nvmem_read_blackbox(data, mem_offset);
> +		if (ret)
> +			dev_err(&data->client->dev, "Could not read blackbox!");
> +		return ret;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int adm1266_nvmem_read(void *priv, unsigned int offset, void *val,
> +			      size_t bytes)
> +{
> +	const struct nvmem_cell_info *mem_cell;
> +	struct adm1266_data *data = priv;
> +	int ret;
> +	int i;
> +
> +	for (i = 0; i < data->nvmem_config.ncells; i++) {
> +		mem_cell = &adm1266_nvmem_cells[i];
> +		if (!adm1266_cell_is_accessed(mem_cell, offset, bytes))
> +			continue;
> +
> +		ret = adm1266_read_mem_cell(data, mem_cell);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
> +	memcpy(val, data->dev_mem + offset, bytes);
> +
> +	return 0;
> +}
> +
> +static int adm1266_config_nvmem(struct adm1266_data *data)
> +{
> +	data->nvmem_config.name = dev_name(&data->client->dev);
> +	data->nvmem_config.dev = &data->client->dev;
> +	data->nvmem_config.root_only = true;
> +	data->nvmem_config.read_only = true;
> +	data->nvmem_config.owner = THIS_MODULE;
> +	data->nvmem_config.reg_read = adm1266_nvmem_read;
> +	data->nvmem_config.cells = adm1266_nvmem_cells;
> +	data->nvmem_config.ncells = ARRAY_SIZE(adm1266_nvmem_cells);
> +	data->nvmem_config.priv = data;
> +	data->nvmem_config.stride = 1;
> +	data->nvmem_config.word_size = 1;
> +	data->nvmem_config.size = 0x80000;
> +
> +	data->nvmem = nvmem_register(&data->nvmem_config);
> +	if (IS_ERR(data->nvmem)) {
> +		dev_err(&data->client->dev, "Could not register nvmem!");
> +		return PTR_ERR(data->nvmem);
> +	}
> +
> +	data->dev_mem = devm_kzalloc(&data->client->dev,
> +				     data->nvmem_config.size,
> +				     GFP_KERNEL);
> +	if (!data->dev_mem)
> +		return -ENOMEM;
> +
> +	return 0;
>  }
>  
>  static int adm1266_probe(struct i2c_client *client,
> @@ -299,6 +455,10 @@ static int adm1266_probe(struct i2c_client *client,
>  	if (ret < 0)
>  		return ret;
>  
> +	ret = adm1266_config_nvmem(data);
> +	if (ret < 0)
> +		return ret;
> +
>  	adm1266_debug_init(data);
>  
>  	info = &data->info;
>