[U-Boot] [PATCH v3 01/10] dm: i2c: Add a uclass for I2C
Heiko Schocher
hs at denx.de
Tue Dec 2 07:29:54 CET 2014
Hello Simon,
Am 02.12.2014 05:31, schrieb Simon Glass:
> +Heiko - are you OK with the new msg-based approach?
Yes, you can add my acked-by to the hole series.
bye,
Heiko
>
>
> Hi Masahiro,
>
> On 1 December 2014 at 04:47, Masahiro Yamada <yamada.m at jp.panasonic.com> wrote:
>> Hi Simon,
>>
>>
>> My review is still under way,
>> but I have some comments below:
>>
>>
>>
>>
>> On Mon, 24 Nov 2014 11:57:15 -0700
>> Simon Glass <sjg at chromium.org> wrote:
>>
>>> +static bool i2c_setup_offset(struct dm_i2c_chip *chip, uint offset,
>>> + uint8_t offset_buf[], struct i2c_msg *msg)
>>> +{
>>> + if (!chip->offset_len)
>>> + return false;
>>> + msg->addr = chip->chip_addr;
>>> + msg->flags = chip->flags;
>>> + msg->len = chip->offset_len;
>>> + msg->buf = offset_buf;
>>
>> You directly copy
>> from (struct dm_i2c_chip *)->flags
>> to (struct i2c_msg *)->flags.
>>
>> But you define completely different flags for them:
>> DM_I2C_CHIP_10BIT is defined as 0x1.
>> I2C_M_TEN is defined as 0x10.
>>
>> It would not work.
>>
>>
>>
>>> +
>>> +static int i2c_read_bytewise(struct udevice *dev, uint offset,
>>> + const uint8_t *buffer, int len)
>>> +{
>>> + struct dm_i2c_chip *chip = dev_get_parentdata(dev);
>>> + struct udevice *bus = dev_get_parent(dev);
>>> + struct dm_i2c_ops *ops = i2c_get_ops(bus);
>>> + struct i2c_msg msg[1];
>>> + uint8_t buf[5];
>>> + int ret;
>>> + int i;
>>> +
>>> + for (i = 0; i < len; i++) {
>>> + i2c_setup_offset(chip, offset, buf, msg);
>>> + msg->len++;
>>> + buf[chip->offset_len] = buffer[i];
>>> +
>>> + ret = ops->xfer(bus, msg, 1);
>>> + if (ret)
>>> + return ret;
>>> + }
>>> +
>>> + return 0;
>>> +}
>>
>> I could not understand how this works.
>> It seems to send only write transactions.
>>
>>
>>
>>> +
>>> +static int i2c_bind_driver(struct udevice *bus, uint chip_addr,
>>> + struct udevice **devp)
>>> +{
>>> + struct dm_i2c_chip *chip;
>>> + char name[30], *str;
>>> + struct udevice *dev;
>>> + int ret;
>>> +
>>> + snprintf(name, sizeof(name), "generic_%x", chip_addr);
>>> + str = strdup(name);
>>> + ret = device_bind_driver(bus, "i2c_generic_drv", str, &dev);
>>> + debug("%s: device_bind_driver: ret=%d\n", __func__, ret);
>>> + if (ret)
>>> + goto err_bind;
>>> +
>>> + /* Tell the device what we know about it */
>>> + chip = calloc(1, sizeof(struct dm_i2c_chip));
>>> + if (!chip) {
>>> + ret = -ENOMEM;
>>> + goto err_mem;
>>> + }
>>> + chip->chip_addr = chip_addr;
>>> + chip->offset_len = 1; /* we assume */
>>> + ret = device_probe_child(dev, chip);
>>> + debug("%s: device_probe_child: ret=%d\n", __func__, ret);
>>> + free(chip);
>>
>>
>> Why do you need calloc() & free() here?
>> I think you can use the stack area for "struct dm_i2c_chip chip;"
>>
>>
>>
>>
>>
>>
>>
>>
>>> +
>>> +UCLASS_DRIVER(i2c) = {
>>> + .id = UCLASS_I2C,
>>> + .name = "i2c",
>>> + .per_device_auto_alloc_size = sizeof(struct dm_i2c_bus),
>>> + .post_bind = i2c_post_bind,
>>> + .post_probe = i2c_post_probe,
>>> +};
>>> +
>>> +UCLASS_DRIVER(i2c_generic) = {
>>> + .id = UCLASS_I2C_GENERIC,
>>> + .name = "i2c_generic",
>>> +};
>>> +
>>> +U_BOOT_DRIVER(i2c_generic_drv) = {
>>
>> Perhaps isn't "i2c_generic_chip" clearer than "i2c_generic_drv"?
>>
>>
>>
>>> + .name = "i2c_generic_drv",
>>> + .id = UCLASS_I2C_GENERIC,
>>> +};
>>
>>
>> Can we move "i2c_generic" to a different file?
>> maybe, drivers/i2c/i2c-generic.c or drivers/i2c/i2c-generic-chip.c ?
>>
>> UCLASS_DRIVER(i2c) is a bus, whereas UCLASS_DRIVER(i2c_generic) is a chip.
>>
>> Mixing up a bus and a chip-device together in the same file
>> looks confusing to me.
>>
>>
>>
>>
>>>
>>> /*
>>> + * For now there are essentially two parts to this file - driver model
>>> + * here at the top, and the older code below (with CONFIG_SYS_I2C being
>>> + * most recent). The plan is to migrate everything to driver model.
>>> + * The driver model structures and API are separate as they are different
>>> + * enough as to be incompatible for compilation purposes.
>>> + */
>>> +
>>> +#ifdef CONFIG_DM_I2C
>>> +
>>> +enum dm_i2c_chip_flags {
>>> + DM_I2C_CHIP_10BIT = 1 << 0, /* Use 10-bit addressing */
>>> + DM_I2C_CHIP_RE_ADDRESS = 1 << 1, /* Send address for every byte */
>>> +};
>>
>>
>> As I mentioned above, you define DM_I2C_CHIP_10BIT as 0x1
>> whereas you define I2C_M_TEN as 0x0010.
>>
>> These flags should be shared with struct i2c_msg.
>>
>>
>>
>>> +/*
>>> + * Not all of these flags are implemented in the U-Boot API
>>> + */
>>> +enum dm_i2c_msg_flags {
>>> + I2C_M_TEN = 0x0010, /* ten-bit chip address */
>>> + I2C_M_RD = 0x0001, /* read data, from slave to master */
>>> + I2C_M_STOP = 0x8000, /* send stop after this message */
>>> + I2C_M_NOSTART = 0x4000, /* no start before this message */
>>> + I2C_M_REV_DIR_ADDR = 0x2000, /* invert polarity of R/W bit */
>>> + I2C_M_IGNORE_NAK = 0x1000, /* continue after NAK */
>>> + I2C_M_NO_RD_ACK = 0x0800, /* skip the Ack bit on reads */
>>> + I2C_M_RECV_LEN = 0x0400, /* length is first received byte */
>>> +};
>>
>> I think this enum usage is odd.
>>
>> If you want to allocate specific values such as 0x8000, 0x4000, etc.
>> you should use #define instead of enum.
>>
>> If you do not care which value is assigned, you can use enum.
>> arch/arm/include/asm/spl.h is a good example of usage of enum.
>>
>>
>>
>>
>>
>>
>>> +};
>>> +
>>> +/**
>>> + * struct dm_i2c_ops - driver operations for I2C uclass
>>> + *
>>> + * Drivers should support these operations unless otherwise noted. These
>>> + * operations are intended to be used by uclass code, not directly from
>>> + * other code.
>>> + */
>>> +struct dm_i2c_ops {
>>> + /**
>>> + * xfer() - transfer a list of I2C messages
>>> + *
>>> + * @bus: Bus to read from
>>> + * @chip_addr: Chip address to read from
>>> + * @offset: Offset within chip to start reading
>>> + * @olen: Length of chip offset in bytes
>>> + * @buffer: Place to put data
>>> + * @len: Number of bytes to read
>>> + * @return 0 if OK, -EREMOTEIO if the slave did not ACK a byte,
>>> + * other -ve value on some other error
>>> + */
>>> + int (*xfer)(struct udevice *bus, struct i2c_msg *msg, int nmsgs);
>>
>>
>> This comment block does not reflect the actual prototype;
>> chip_addr, offset, ... etc. do not exist any more.
>
> Thanks for these comments, I will work on another version soon.
>
> Regards,
> Simon
>
--
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
More information about the U-Boot
mailing list