On 12/13/22 10:18, Alexandre Belloni wrote:
> On 05/12/2022 10:19:18-0500, Sean Anderson wrote:
>> This adds support for the 256-byte internal RAM. There are two windows
>> which can be used to access this RAM: 64 bytes at 0x40 (the "standard"
>> address space) and 128 bytes at 0x80 (the "alternate" address space). We
>> use the standard address space because it is also accessible over SPI
>> (if such a port is ever done). We are limited to 32-byte reads for SMBus
>> compatibility, so there's no advantage to using the alternate address
>> space.
>>
>> There are some reserved bits in the EXTRAM register, and the datasheet
>> doesn't say what to do with them. I've opted to skip a read/modify/write
>> and just write the whole thing. If this driver is ever converted to
>> regmap, this would be a good place to use regmap_update_bits.
>>
>> Signed-off-by: Sean Anderson <sean.anderson@xxxxxxxx>
>> ---
>>
>> Changes in v2:
>> - Fix building on non-arm platforms
>>
>> drivers/rtc/rtc-abx80x.c | 87 ++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 87 insertions(+)
>>
>> diff --git a/drivers/rtc/rtc-abx80x.c b/drivers/rtc/rtc-abx80x.c
>> index 9b0138d07232..e606bf126dc3 100644
>> --- a/drivers/rtc/rtc-abx80x.c
>> +++ b/drivers/rtc/rtc-abx80x.c
>> @@ -11,6 +11,7 @@
>> */
>>
>> #include <linux/bcd.h>
>> +#include <linux/bitfield.h>
>> #include <linux/i2c.h>
>> #include <linux/module.h>
>> #include <linux/of_device.h>
>> @@ -87,6 +88,16 @@
>> #define ABX8XX_TRICKLE_STANDARD_DIODE 0x8
>> #define ABX8XX_TRICKLE_SCHOTTKY_DIODE 0x4
>>
>> +#define ABX8XX_REG_EXTRAM 0x3f
>> +#define ABX8XX_EXTRAM_XADS GENMASK(1, 0)
>> +
>> +#define ABX8XX_SRAM_BASE 0x40
>> +#define ABX8XX_SRAM_WIN_SIZE 0x40
>> +#define ABX8XX_RAM_SIZE 256
>> +
>> +#define NVMEM_ADDR_LOWER GENMASK(5, 0)
>> +#define NVMEM_ADDR_UPPER GENMASK(7, 6)
>> +
>> static u8 trickle_resistors[] = {0, 3, 6, 11};
>>
>> enum abx80x_chip {AB0801, AB0803, AB0804, AB0805,
>> @@ -673,6 +684,78 @@ static int abx80x_setup_watchdog(struct abx80x_priv *priv)
>> }
>> #endif
>>
>> +#ifdef CONFIG_NVMEM
>> +static int abx80x_nvmem_xfer(struct abx80x_priv *priv, unsigned int offset,
>> + void *val, size_t bytes, bool write)
>> +{
>> + int ret;
>> +
>> + while (bytes) {
>> + u8 extram, reg, len, lower, upper;
>> +
>> + lower = FIELD_GET(NVMEM_ADDR_LOWER, offset);
>> + upper = FIELD_GET(NVMEM_ADDR_UPPER, offset);
>> + extram = FIELD_PREP(ABX8XX_EXTRAM_XADS, upper);
>> + reg = ABX8XX_SRAM_BASE + lower;
>> + len = min(lower + bytes, (size_t)ABX8XX_SRAM_WIN_SIZE) - lower;
>> + len = min_t(u8, len, I2C_SMBUS_BLOCK_MAX);
>> +
>> + ret = i2c_smbus_write_byte_data(priv->client, ABX8XX_REG_EXTRAM,
>> + extram);
>> + if (ret)
>> + return ret;
>> +
>> + if (write)
>> + ret = i2c_smbus_write_i2c_block_data(priv->client, reg,
>> + len, val);
>> + else
>> + ret = i2c_smbus_read_i2c_block_data(priv->client, reg,
>> + len, val);
>> + if (ret)
>> + return ret;
>> +
>> + offset += len;
>> + val += len;
>> + bytes -= len;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int abx80x_nvmem_read(void *priv, unsigned int offset, void *val,
>> + size_t bytes)
>> +{
>> + return abx80x_nvmem_xfer(priv, offset, val, bytes, false);
>> +}
>> +
>> +static int abx80x_nvmem_write(void *priv, unsigned int offset, void *val,
>> + size_t bytes)
>> +{
>> + return abx80x_nvmem_xfer(priv, offset, val, bytes, true);
>> +}
>> +
>> +static int abx80x_setup_nvmem(struct abx80x_priv *priv)
>> +{
>> + struct device *dev = &priv->client->dev;
>> + struct nvmem_config config = {
>> + .dev = dev,
>> + .type = NVMEM_TYPE_BATTERY_BACKED,
>> + .reg_read = abx80x_nvmem_read,
>> + .reg_write = abx80x_nvmem_write,
>> + .size = ABX8XX_RAM_SIZE,
>> + .priv = priv,
>> + };
>> +
>> + return PTR_ERR_OR_ZERO(devm_nvmem_register(&priv->client->dev,
>> + &config));
>
> Is there any reason why you are not using devm_rtc_nvmem_register ?
>
>
I didn't know it existed. To be honest, it doesn't seem to be doing much.
With that changed, is the rest of the patch OK?
--Sean
