[U-Boot] [PATCH 2/2] dm: gpio: introduce 74x164 driver

[Peng Fan <van.freenix@gmail.com>]

Hi Simon,

Thanks for reviewing.

On Sat, Apr 09, 2016 at 12:33:40PM -0600, Simon Glass wrote:
>Hi Peng,
>
>On 21 March 2016 at 02:29, Peng Fan <van.freenix@gmail.com> wrote:
>> Introduce driver to support "fairchild,74hc595" devices.
>> 1. Take linux drivers/drivers/gpio/gpio-74x164.c as reference.
>> 2. Following the naming used in Linux driver with gen_7x164 as the prefix.
>> 3. Enable CONFIG_DM_74X164 to use this driver.
>> 4. Follow Documentation/devicetree/bindings/gpio/gpio-74x164.txt to add device
>>    nodes
>> 5. Tested on i.MX6 UltraLite with 74LV595 using gpio command and oscillograph.
>>
>> Signed-off-by: Peng Fan <van.freenix@gmail.com>
>> Cc: Simon Glass <sjg@chromium.org>
>> Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
>> Cc: Chin Liang See <clsee@altera.com>
>> Cc: Bhuvanchandra DV <bhuvanchandra.dv@toradex.com>
>> Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
>> Cc: Fabio Estevam <fabio.estevam@nxp.com>
>> Cc: Stefano Babic <sbabic@denx.de>
>> ---
>>  drivers/gpio/74x164_gpio.c | 220 +++++++++++++++++++++++++++++++++++++++++++++
>>  drivers/gpio/Kconfig       |   8 ++
>>  drivers/gpio/Makefile      |   1 +
>>  3 files changed, 229 insertions(+)
>>  create mode 100644 drivers/gpio/74x164_gpio.c
>>
>> diff --git a/drivers/gpio/74x164_gpio.c b/drivers/gpio/74x164_gpio.c
>> new file mode 100644
>> index 0000000..5d12a9a
>> --- /dev/null
>> +++ b/drivers/gpio/74x164_gpio.c
>> @@ -0,0 +1,220 @@
>> +/*
>> + * Take drivers/gpio/gpio-74x164.c as reference.
>> + *
>> + * 74Hx164 - Generic serial-in/parallel-out 8-bits shift register GPIO driver
>> + *
>> + * Copyright (C) 2016 Peng Fan <van.freenix@gmail.com>
>> + *
>> + * SPDX-License-Identifier:    GPL-2.0+
>> + *
>> + */
>> +
>> +#include <common.h>
>> +#include <errno.h>
>> +#include <dm.h>
>> +#include <fdtdec.h>
>> +#include <malloc.h>
>> +#include <asm/gpio.h>
>> +#include <asm/io.h>
>> +#include <dt-bindings/gpio/gpio.h>
>> +#include <spi.h>
>> +
>> +DECLARE_GLOBAL_DATA_PTR;
>> +
>> +/*
>> + * struct gen_74x164_chip - Data for 74Hx164
>> + *
>> + * @dev: udevice structure for the device
>
>This doesn't appear to be u
>> + * @slave: spi slave
>> + * @oe: OE pin
>> + * @nregs: number of registers
>> + * @buffer: buffer for chained chips
>> + */
>> +#define GEN_74X164_NUMBER_GPIOS 8
>> +
>> +struct gen_74x164_info {
>
>How about gen_74x164_priv?
>
>> +       struct udevice *dev;
>
>This doesn't seem to be used

Will drop it in V2.

>
>> +       struct spi_slave *slave;
>> +       struct gpio_desc oe;
>> +       u32 nregs;
>> +       /*
>> +        * Since the nregs are chained, every byte sent will make
>> +        * the previous byte shift to the next register in the
>> +        * chain. Thus, the first byte sent will end up in the last
>> +        * register at the end of the transfer. So, to have a logical
>> +        * numbering, store the bytes in reverse order.
>> +        */
>> +       u8 *buffer;
>> +};
>> +
>> +static int gen_74x164_write_conf(struct udevice *dev)
>> +{
>> +       struct gen_74x164_info *info = dev_get_platdata(dev);
>> +       struct spi_slave *slave = info->slave;
>> +       int ret;
>> +
>> +       ret = spi_claim_bus(slave);
>> +       if (ret)
>> +               return ret;
>> +
>> +       ret = spi_xfer(slave, info->nregs * 8, info->buffer, NULL,
>> +                      SPI_XFER_BEGIN | SPI_XFER_END);
>> +
>> +       spi_release_bus(slave);
>> +
>> +       return ret;
>> +}
>> +
>> +static int gen_74x164_get_value(struct udevice *dev, unsigned offset)
>> +{
>> +       struct gen_74x164_info *info = dev_get_platdata(dev);
>> +       u8 bank = info->nregs - 1 - offset / 8;
>> +       u8 pin = offset % 8;
>> +
>> +       return (info->buffer[bank] >> pin) & 0x1;
>> +}
>> +
>> +static int gen_74x164_set_value(struct udevice *dev, unsigned offset,
>> +                               int value)
>> +{
>> +       struct gen_74x164_info *info = dev_get_platdata(dev);
>> +       u8 bank = info->nregs - 1 - offset / 8;
>> +       u8 pin = offset % 8;
>
>uint should be good enough for these

Fix in V2.

>
>> +       int ret;
>> +
>> +       if (value)
>> +               info->buffer[bank] |= 1 << pin;
>> +       else
>> +               info->buffer[bank] &= ~(1 << pin);
>> +
>> +       ret = gen_74x164_write_conf(dev);
>> +       if (ret)
>> +               return ret;
>> +
>> +       return 0;
>> +}
>> +
>> +static int gen_74x164_direction_input(struct udevice *dev, unsigned offset)
>> +{
>> +       return -EINVAL;
>
>-ENOSYS if it is not supported

Fix in V2.

>
>> +}
>> +
>> +static int gen_74x164_direction_output(struct udevice *dev, unsigned offset,
>> +                                     int value)
>> +{
>
>> +       return gen_74x164_set_value(dev, offset, value);
>> +}
>> +
>> +static int gen_74x164_get_function(struct udevice *dev, unsigned offset)
>> +{
>> +       return GPIOF_OUTPUT;
>> +}
>> +
>> +static int gen_74x164_xlate(struct udevice *dev, struct gpio_desc *desc,
>> +                           struct fdtdec_phandle_args *args)
>> +{
>> +       desc->offset = args->args[0];
>> +       desc->flags = args->args[1] & GPIO_ACTIVE_LOW ? GPIOD_ACTIVE_LOW : 0;
>> +
>> +       return 0;
>> +}
>> +
>> +static const struct dm_gpio_ops gen_74x164_ops = {
>> +       .direction_input        = gen_74x164_direction_input,
>> +       .direction_output       = gen_74x164_direction_output,
>> +       .get_value              = gen_74x164_get_value,
>> +       .set_value              = gen_74x164_set_value,
>> +       .get_function           = gen_74x164_get_function,
>> +       .xlate                  = gen_74x164_xlate,
>> +};
>> +
>> +static int gen_74x164_probe(struct udevice *dev)
>> +{
>> +       struct gen_74x164_info *info = dev_get_platdata(dev);
>> +       struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
>> +       char *str, *str1;
>> +       int ret;
>> +       const void *fdt = gd->fdt_blob;
>> +       int node = dev->of_offset;
>> +       struct udevice *bus;
>> +       int busnum;
>> +       char name[30];
>> +
>> +       str = strdup(dev->name);
>> +       if (!str)
>> +               return -ENOMEM;
>> +
>> +       info->nregs = fdtdec_get_int(fdt, node, "registers-number", 1);
>
>Do you have a device tree binding file you can add for this?

In Kernel:
Documentation/devicetree/bindings/gpio/gpio-74x164.txt

>
>> +       info->buffer = calloc(info->nregs, sizeof(u8));
>> +       if (!info->buffer) {
>> +               ret = -ENOMEM;
>> +               goto free_str;
>> +       }
>
>What's the largest number of registers you can have? If it is small,
>like 32, consider making buffer a simple fixed-length array.

In general usage, only 1, but follow kernel, designed to be chained.
So we do not have fixed value.

>
>> +
>> +       ret = fdtdec_get_byte_array(fdt, node, "registers-default",
>> +                                   info->buffer, info->nregs);
>> +       if (ret)
>> +               dev_dbg(dev, "No registers-default property\n");
>> +
>> +       ret = gpio_request_by_name(dev, "oe-gpios", 0, &info->oe,
>> +                                  GPIOD_IS_OUT | GPIOD_IS_OUT_ACTIVE);
>> +       if (ret) {
>> +               dev_err(dev, "No oe-pins property\n");
>> +               goto free_buf;
>> +       }
>> +
>> +       /* output enable */
>> +       ret = dm_gpio_set_value(&info->oe, 0);
>> +       if (ret) {
>> +               dev_err(dev, "Set oe-pins value failure\n");
>> +               goto free_buf;
>> +       }
>
>
>The GPIOD_IS_OUT_ACTIVE above will already activate this GPIO.

Will fix in V2.

>
>> +
>> +       uc_priv->bank_name = str;
>> +       uc_priv->gpio_count = info->nregs * 8;
>> +
>> +       bus = dev_get_parent(dev);
>> +       busnum = bus->seq;
>> +
>> +       snprintf(name, sizeof(name), "generic_%d:%d", busnum, 0);
>> +       str1 = strdup(name);
>
>What is str1 used for?

Oh. Should be used for spi_get_bus_and_cs, will fix in V2.
>
>> +       if (!str1) {
>> +               ret = -ENOMEM;
>> +               goto free_buf;
>> +       }
>> +
>> +       ret = spi_get_bus_and_cs(busnum, 0, 1000000, SPI_MODE_0,
>> +                                "spi_generic_drv", str, &bus, &info->slave);
>> +       if (ret)
>> +               goto free_str1;
>
>Why do you need this? The parent device is the SPI bus. See
>drivers/misc/cros_ec_spi.c for how it probes. There really shouldn't
>be much to do.
>
>I'd suggest:
>
>infp->slave = dev_get_parent_priv(dev);

Ok. Will try this. Fix in V2.

>
>> +
>> +       ret = gen_74x164_write_conf(dev);
>> +       if (ret)
>> +               goto free_str1;
>> +
>> +       dev_dbg(dev, "%s is ready\n", dev->name);
>> +
>> +       return 0;
>> +
>> +free_str1:
>> +       free(str1);
>> +free_buf:
>> +       free(info->buffer);
>> +free_str:
>> +       free(str);
>> +       return ret;
>> +}
>> +
>> +static const struct udevice_id gen_74x164_ids[] = {
>> +       { .compatible = "fairchild,74hc595" },
>> +       { }
>> +};
>> +
>> +U_BOOT_DRIVER(74x164) = {
>> +       .name           = "74x164",
>> +       .id             = UCLASS_GPIO,
>> +       .ops            = &gen_74x164_ops,
>> +       .probe          = gen_74x164_probe,
>> +       .platdata_auto_alloc_size = sizeof(struct gen_74x164_info),
>
>It does not seem to be used before probe(), so I think this should be
>priv_auto_alloc_size.

Fix in V2.

>
>> +       .of_match       = gen_74x164_ids,
>> +};
>> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
>> index 51658f1..43fc9c4 100644
>> --- a/drivers/gpio/Kconfig
>> +++ b/drivers/gpio/Kconfig
>> @@ -96,6 +96,14 @@ config PIC32_GPIO
>>         help
>>           Say yes here to support Microchip PIC32 GPIOs.
>>
>> +config DM_74X164
>> +       bool "74x164 serial-in/parallel-out 8-bits shift register"
>> +       depends on DM_GPIO
>> +       help
>> +         Driver for 74x164 compatible serial-in/parallel-out 8-outputs
>
>74x164-compatible
>
>Should you mention the oriiginal manufacturer. Also you could mention
>that it uses SPI.

Will fix in V2.

>
>> +         shift registers. This driver can be used to provide access
>> +         to more gpio outputs.
>> +
>>  config DM_PCA953X
>>         bool "PCA95[357]x, PCA9698, TCA64xx, and MAX7310 I/O ports"
>>         depends on DM_GPIO
>> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
>> index bfc67d2..393b148 100644
>> --- a/drivers/gpio/Makefile
>> +++ b/drivers/gpio/Makefile
>> @@ -12,6 +12,7 @@ endif
>>  obj-$(CONFIG_DM_GPIO)          += gpio-uclass.o
>>
>>  obj-$(CONFIG_DM_PCA953X)       += pca953x_gpio.o
>> +obj-$(CONFIG_DM_74X164)                += 74x164_gpio.o
>>
>>  obj-$(CONFIG_AT91_GPIO)        += at91_gpio.o
>>  obj-$(CONFIG_ATMEL_PIO4)       += atmel_pio4.o
>> --
>> 2.6.2
>>
>
>Regards,
>Simon