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SubjectRe: [PATCH v2] iio/chemical/bme680: Fix SPI read interface
Date
On 03-03-19 17:57, Jonathan Cameron wrote:
> On Thu, 21 Feb 2019 10:20:49 +0100
> Mike Looijmans <mike.looijmans@topic.nl> wrote:
>
>> The SPI interface implementation was completely broken.
>>
>> When using the SPI interface, there are only 7 address bits, the upper bit
>> is controlled by a page select register. The core needs access to both
>> ranges, so implement register read/write for both regions. The regmap
>> paging functionality didn't agree with a register that needs to be read
>> and modified, so I implemented a custom paging algorithm.
>>
>> This fixes that the device wouldn't even probe in SPI mode.
>>
>> The SPI interface then isn't different from I2C, merged them into the core,
>> and the I2C/SPI named registers are no longer needed.
>>
>> Implemented register value caching for the registers to reduce the I2C/SPI
>> data transfers considerably.
>>
>> The calibration set reads as all zeroes until some undefined point in time,
>> and I couldn't determine what makes it valid. The datasheet mentions these
>> registers but does not provide any hints on when they become valid, and they
>> aren't even enumerated in the memory map. So check the calibration and
>> retry reading it from the device after each measurement until it provides
>> something valid.
>>
>> Report temperature in millidegrees Celcius instead of degrees.
> Hi Mike,
>
> This last bit is an unrelated issue. Would you mind splitting the patch into two?
> Please put the temperature one first as that is definitely a stable
> worthy patch. The larger one is more debatable as it seems that it
> never worked and is a fairly large patch.
>
> I'll probably mark them both for stable, but it is possible not all
> the stable branches will pick them both up.

Splitting the patch was easy enough, the're independent, I'll post a v3 with
both patches.


>
> Thanks,
>
> Jonathan
>
>>
>> Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
>> ---
>> v2: Remove unused 'addr7' variable
>>
>> drivers/iio/chemical/bme680.h | 6 +-
>> drivers/iio/chemical/bme680_core.c | 54 ++++++++++++++---
>> drivers/iio/chemical/bme680_i2c.c | 21 -------
>> drivers/iio/chemical/bme680_spi.c | 115 +++++++++++++++++++++++++------------
>> 4 files changed, 125 insertions(+), 71 deletions(-)
>>
>> diff --git a/drivers/iio/chemical/bme680.h b/drivers/iio/chemical/bme680.h
>> index 0ae89b87..4edc5d21 100644
>> --- a/drivers/iio/chemical/bme680.h
>> +++ b/drivers/iio/chemical/bme680.h
>> @@ -2,11 +2,9 @@
>> #ifndef BME680_H_
>> #define BME680_H_
>>
>> -#define BME680_REG_CHIP_I2C_ID 0xD0
>> -#define BME680_REG_CHIP_SPI_ID 0x50
>> +#define BME680_REG_CHIP_ID 0xD0
>> #define BME680_CHIP_ID_VAL 0x61
>> -#define BME680_REG_SOFT_RESET_I2C 0xE0
>> -#define BME680_REG_SOFT_RESET_SPI 0x60
>> +#define BME680_REG_SOFT_RESET 0xE0
>> #define BME680_CMD_SOFTRESET 0xB6
>> #define BME680_REG_STATUS 0x73
>> #define BME680_SPI_MEM_PAGE_BIT BIT(4)
>> diff --git a/drivers/iio/chemical/bme680_core.c b/drivers/iio/chemical/bme680_core.c
>> index 70c1fe4..ccde4c6 100644
>> --- a/drivers/iio/chemical/bme680_core.c
>> +++ b/drivers/iio/chemical/bme680_core.c
>> @@ -63,9 +63,23 @@ struct bme680_data {
>> s32 t_fine;
>> };
>>
>> +static const struct regmap_range bme680_volatile_ranges[] = {
>> + regmap_reg_range(BME680_REG_MEAS_STAT_0, BME680_REG_GAS_R_LSB),
>> + regmap_reg_range(BME680_REG_STATUS, BME680_REG_STATUS),
>> + regmap_reg_range(BME680_T2_LSB_REG, BME680_GH3_REG),
>> +};
>> +
>> +static const struct regmap_access_table bme680_volatile_table = {
>> + .yes_ranges = bme680_volatile_ranges,
>> + .n_yes_ranges = ARRAY_SIZE(bme680_volatile_ranges),
>> +};
>> +
>> const struct regmap_config bme680_regmap_config = {
>> .reg_bits = 8,
>> .val_bits = 8,
>> + .max_register = 0xef,
>> + .volatile_table = &bme680_volatile_table,
>> + .cache_type = REGCACHE_RBTREE,
>> };
>> EXPORT_SYMBOL(bme680_regmap_config);
>>
>> @@ -316,6 +330,10 @@ static s16 bme680_compensate_temp(struct bme680_data *data,
>> s64 var1, var2, var3;
>> s16 calc_temp;
>>
>> + /* If the calibration is invalid, attempt to reload it */
>> + if (!calib->par_t2)
>> + bme680_read_calib(data, calib);
>> +
>> var1 = (adc_temp >> 3) - (calib->par_t1 << 1);
>> var2 = (var1 * calib->par_t2) >> 11;
>> var3 = ((var1 >> 1) * (var1 >> 1)) >> 12;
>> @@ -583,8 +601,7 @@ static int bme680_gas_config(struct bme680_data *data)
>> return ret;
>> }
>>
>> -static int bme680_read_temp(struct bme680_data *data,
>> - int *val, int *val2)
>> +static int bme680_read_temp(struct bme680_data *data, int *val)
>> {
>> struct device *dev = regmap_get_device(data->regmap);
>> int ret;
>> @@ -617,10 +634,9 @@ static int bme680_read_temp(struct bme680_data *data,
>> * compensate_press/compensate_humid to get compensated
>> * pressure/humidity readings.
>> */
>> - if (val && val2) {
>> - *val = comp_temp;
>> - *val2 = 100;
>> - return IIO_VAL_FRACTIONAL;
>> + if (val) {
>> + *val = comp_temp * 10; /* Centidegrees to millidegrees */
>> + return IIO_VAL_INT;
>> }
>>
>> return ret;
>> @@ -635,7 +651,7 @@ static int bme680_read_press(struct bme680_data *data,
>> s32 adc_press;
>>
>> /* Read and compensate temperature to get a reading of t_fine */
>> - ret = bme680_read_temp(data, NULL, NULL);
>> + ret = bme680_read_temp(data, NULL);
>> if (ret < 0)
>> return ret;
>>
>> @@ -668,7 +684,7 @@ static int bme680_read_humid(struct bme680_data *data,
>> u32 comp_humidity;
>>
>> /* Read and compensate temperature to get a reading of t_fine */
>> - ret = bme680_read_temp(data, NULL, NULL);
>> + ret = bme680_read_temp(data, NULL);
>> if (ret < 0)
>> return ret;
>>
>> @@ -761,7 +777,7 @@ static int bme680_read_raw(struct iio_dev *indio_dev,
>> case IIO_CHAN_INFO_PROCESSED:
>> switch (chan->type) {
>> case IIO_TEMP:
>> - return bme680_read_temp(data, val, val2);
>> + return bme680_read_temp(data, val);
>> case IIO_PRESSURE:
>> return bme680_read_press(data, val, val2);
>> case IIO_HUMIDITYRELATIVE:
>> @@ -867,8 +883,28 @@ int bme680_core_probe(struct device *dev, struct regmap *regmap,
>> {
>> struct iio_dev *indio_dev;
>> struct bme680_data *data;
>> + unsigned int val;
>> int ret;
>>
>> + ret = regmap_write(regmap, BME680_REG_SOFT_RESET,
>> + BME680_CMD_SOFTRESET);
>> + if (ret < 0) {
>> + dev_err(dev, "Failed to reset chip\n");
>> + return ret;
>> + }
>> +
>> + ret = regmap_read(regmap, BME680_REG_CHIP_ID, &val);
>> + if (ret < 0) {
>> + dev_err(dev, "Error reading chip ID\n");
>> + return ret;
>> + }
>> +
>> + if (val != BME680_CHIP_ID_VAL) {
>> + dev_err(dev, "Wrong chip ID, got %x expected %x\n",
>> + val, BME680_CHIP_ID_VAL);
>> + return -ENODEV;
>> + }
>> +
>> indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
>> if (!indio_dev)
>> return -ENOMEM;
>> diff --git a/drivers/iio/chemical/bme680_i2c.c b/drivers/iio/chemical/bme680_i2c.c
>> index 06d4be5..cfc4449 100644
>> --- a/drivers/iio/chemical/bme680_i2c.c
>> +++ b/drivers/iio/chemical/bme680_i2c.c
>> @@ -23,8 +23,6 @@ static int bme680_i2c_probe(struct i2c_client *client,
>> {
>> struct regmap *regmap;
>> const char *name = NULL;
>> - unsigned int val;
>> - int ret;
>>
>> regmap = devm_regmap_init_i2c(client, &bme680_regmap_config);
>> if (IS_ERR(regmap)) {
>> @@ -33,25 +31,6 @@ static int bme680_i2c_probe(struct i2c_client *client,
>> return PTR_ERR(regmap);
>> }
>>
>> - ret = regmap_write(regmap, BME680_REG_SOFT_RESET_I2C,
>> - BME680_CMD_SOFTRESET);
>> - if (ret < 0) {
>> - dev_err(&client->dev, "Failed to reset chip\n");
>> - return ret;
>> - }
>> -
>> - ret = regmap_read(regmap, BME680_REG_CHIP_I2C_ID, &val);
>> - if (ret < 0) {
>> - dev_err(&client->dev, "Error reading I2C chip ID\n");
>> - return ret;
>> - }
>> -
>> - if (val != BME680_CHIP_ID_VAL) {
>> - dev_err(&client->dev, "Wrong chip ID, got %x expected %x\n",
>> - val, BME680_CHIP_ID_VAL);
>> - return -ENODEV;
>> - }
>> -
>> if (id)
>> name = id->name;
>>
>> diff --git a/drivers/iio/chemical/bme680_spi.c b/drivers/iio/chemical/bme680_spi.c
>> index c9fb05e..881778e 100644
>> --- a/drivers/iio/chemical/bme680_spi.c
>> +++ b/drivers/iio/chemical/bme680_spi.c
>> @@ -11,28 +11,93 @@
>>
>> #include "bme680.h"
>>
>> +struct bme680_spi_bus_context {
>> + struct spi_device *spi;
>> + u8 current_page;
>> +};
>> +
>> +/*
>> + * In SPI mode there are only 7 address bits, a "page" register determines
>> + * which part of the 8-bit range is active. This function looks at the address
>> + * and writes the page selection bit if needed
>> + */
>> +static int bme680_regmap_spi_select_page(
>> + struct bme680_spi_bus_context *ctx, u8 reg)
>> +{
>> + struct spi_device *spi = ctx->spi;
>> + int ret;
>> + u8 buf[2];
>> + u8 page = (reg & 0x80) ? 0 : 1; /* Page "1" is low range */
>> +
>> + if (page == ctx->current_page)
>> + return 0;
>> +
>> + /*
>> + * Data sheet claims we're only allowed to change bit 4, so we must do
>> + * a read-modify-write on each and every page select
>> + */
>> + buf[0] = BME680_REG_STATUS;
>> + ret = spi_write_then_read(spi, buf, 1, buf + 1, 1);
>> + if (ret < 0) {
>> + dev_err(&spi->dev, "failed to set page %u\n", page);
>> + return ret;
>> + }
>> +
>> + buf[0] = BME680_REG_STATUS;
>> + if (page)
>> + buf[1] |= BME680_SPI_MEM_PAGE_BIT;
>> + else
>> + buf[1] &= ~BME680_SPI_MEM_PAGE_BIT;
>> +
>> + ret = spi_write(spi, buf, 2);
>> + if (ret < 0) {
>> + dev_err(&spi->dev, "failed to set page %u\n", page);
>> + return ret;
>> + }
>> +
>> + ctx->current_page = page;
>> +
>> + return 0;
>> +}
>> +
>> static int bme680_regmap_spi_write(void *context, const void *data,
>> size_t count)
>> {
>> - struct spi_device *spi = context;
>> + struct bme680_spi_bus_context *ctx = context;
>> + struct spi_device *spi = ctx->spi;
>> + int ret;
>> u8 buf[2];
>>
>> memcpy(buf, data, 2);
>> +
>> + ret = bme680_regmap_spi_select_page(ctx, buf[0]);
>> + if (ret)
>> + return ret;
>> +
>> /*
>> * The SPI register address (= full register address without bit 7)
>> * and the write command (bit7 = RW = '0')
>> */
>> buf[0] &= ~0x80;
>>
>> - return spi_write_then_read(spi, buf, 2, NULL, 0);
>> + return spi_write(spi, buf, 2);
>> }
>>
>> static int bme680_regmap_spi_read(void *context, const void *reg,
>> size_t reg_size, void *val, size_t val_size)
>> {
>> - struct spi_device *spi = context;
>> + struct bme680_spi_bus_context *ctx = context;
>> + struct spi_device *spi = ctx->spi;
>> + int ret;
>> + u8 addr = *(const u8 *)reg;
>> +
>> + ret = bme680_regmap_spi_select_page(ctx, addr);
>> + if (ret)
>> + return ret;
>>
>> - return spi_write_then_read(spi, reg, reg_size, val, val_size);
>> + addr |= 0x80; /* bit7 = RW = '1' */
>> +
>> + return spi_write_then_read(spi, &addr, 1, val, val_size);
>> }
>>
>> static struct regmap_bus bme680_regmap_bus = {
>> @@ -45,8 +110,8 @@ static int bme680_regmap_spi_read(void *context, const void *reg,
>> static int bme680_spi_probe(struct spi_device *spi)
>> {
>> const struct spi_device_id *id = spi_get_device_id(spi);
>> + struct bme680_spi_bus_context *bus_context;
>> struct regmap *regmap;
>> - unsigned int val;
>> int ret;
>>
>> spi->bits_per_word = 8;
>> @@ -56,45 +121,21 @@ static int bme680_spi_probe(struct spi_device *spi)
>> return ret;
>> }
>>
>> + bus_context = devm_kzalloc(&spi->dev, sizeof(*bus_context), GFP_KERNEL);
>> + if (!bus_context)
>> + return -ENOMEM;
>> +
>> + bus_context->spi = spi;
>> + bus_context->current_page = 0xff; /* Undefined on warm boot */
>> +
>> regmap = devm_regmap_init(&spi->dev, &bme680_regmap_bus,
>> - &spi->dev, &bme680_regmap_config);
>> + bus_context, &bme680_regmap_config);
>> if (IS_ERR(regmap)) {
>> dev_err(&spi->dev, "Failed to register spi regmap %d\n",
>> (int)PTR_ERR(regmap));
>> return PTR_ERR(regmap);
>> }
>>
>> - ret = regmap_write(regmap, BME680_REG_SOFT_RESET_SPI,
>> - BME680_CMD_SOFTRESET);
>> - if (ret < 0) {
>> - dev_err(&spi->dev, "Failed to reset chip\n");
>> - return ret;
>> - }
>> -
>> - /* after power-on reset, Page 0(0x80-0xFF) of spi_mem_page is active */
>> - ret = regmap_read(regmap, BME680_REG_CHIP_SPI_ID, &val);
>> - if (ret < 0) {
>> - dev_err(&spi->dev, "Error reading SPI chip ID\n");
>> - return ret;
>> - }
>> -
>> - if (val != BME680_CHIP_ID_VAL) {
>> - dev_err(&spi->dev, "Wrong chip ID, got %x expected %x\n",
>> - val, BME680_CHIP_ID_VAL);
>> - return -ENODEV;
>> - }
>> - /*
>> - * select Page 1 of spi_mem_page to enable access to
>> - * to registers from address 0x00 to 0x7F.
>> - */
>> - ret = regmap_write_bits(regmap, BME680_REG_STATUS,
>> - BME680_SPI_MEM_PAGE_BIT,
>> - BME680_SPI_MEM_PAGE_1_VAL);
>> - if (ret < 0) {
>> - dev_err(&spi->dev, "failed to set page 1 of spi_mem_page\n");
>> - return ret;
>> - }
>> -
>> return bme680_core_probe(&spi->dev, regmap, id->name);
>> }
>>
>

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