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SubjectRe: [PATCH v2 1/3] mfd: upboard: Add UP2 platform controller driver
On Fri, Oct 19, 2018 at 8:26 PM Dan O'Donovan <dan@emutex.com> wrote:
>
> From: Javier Arteaga <javier@emutex.com>
>
> UP Squared (UP2) is a x86 SBC from AAEON based on Intel Apollo Lake. It
> features a MAX 10 FPGA that routes lines from both SoC and on-board
> devices to two I/O headers:
>
> +------------------------+
> | 40-pin RPi-like header |
> +------| (HAT) |
> | +------------------------+
> +-------+ +--------+
> | | | | +------------------------+
> | SoC |----| FPGA |-----| Custom UP2 pin header |
> | | | | | (EXHAT) |
> +-------+ +--------+ +------------------------+
> |
> +------* On-board devices: LED, VLS...
>
> This is intended to enable vendor-specific applications to customize I/O
> header pinout, as well as include low-latency functionality. It also
> performs voltage level translation between the SoC (1.8V) and HAT header
> (3.3V).
>
> Out of the box, this block implements a platform controller with a
> GPIO-bitbanged control interface. It's enumerated by ACPI and provides
> registers to control:
>
> - Configuration of all FPGA-routed header lines. These can be driven
> SoC-to-header, header-to-SoC or set in high impedance.
>
> - On-board LEDs and enable lines for other platform devices.
>
> Add core support for this platform controller as a MFD device, exposing
> these registers as a regmap.

Can we see a link to or an excerpt of ACPI table for this device?

> +#define set_clear(u, x) gpiod_set_value((u)->clear_gpio, (x))
> +#define set_strobe(u, x) gpiod_set_value((u)->strobe_gpio, (x))
> +#define set_datain(u, x) gpiod_set_value((u)->datain_gpio, (x))
> +#define get_dataout(u) gpiod_get_value((u)->dataout_gpio)

I think these macros don't bring much value. (Up to you and Lee to decide)


> +static void __reg_io_write(const struct upboard_ddata * const ddata,
> + unsigned int size, unsigned int val)
> +{
> + int i;
> +
> + /*
> + * DATAIN is latched on each rising edge of the STROBE signal.
> + * Data (register address or value) is sent MSb first.
> + */

> + for (i = size - 1; i >= 0; i--) {

while (size--)

> + set_strobe(ddata, 0);
> + set_datain(ddata, (val >> i) & 0x1);
> + set_strobe(ddata, 1);
> + }
> +}
> +
> +static void __reg_io_read(const struct upboard_ddata * const ddata,
> + unsigned int size, unsigned int *val)
> +{
> + int i;
> +
> + /*
> + * DATAOUT is latched on on each rising edge of the STROBE signal.
> + * Data (register value) is received MSb first.
> + */
> + *val = 0;

> + for (i = size - 1; i >= 0; i--) {

Ditto.

> + set_strobe(ddata, 0);
> + set_strobe(ddata, 1);
> + *val |= get_dataout(ddata) << i;
> + }
> +}

> +static int upboard_check_supported(struct device *dev, struct regmap *regmap)
> +{
> + uint8_t manufacturer_id, build, major, minor, patch;
> + unsigned int platform_id, firmware_id;
> + int ret;

> + manufacturer_id = platform_id & 0xff;

Redundant & 0xff part.

> + if (manufacturer_id != AAEON_MANUFACTURER_ID) {
> + dev_err(dev,
> + "unsupported FPGA firmware from manufacturer 0x%02x",
> + manufacturer_id);
> + return -ENODEV;
> + }

> +static int upboard_match_device(struct device *dev)
> +{
> + struct upboard_ddata *ddata = dev_get_drvdata(dev);
> + const struct acpi_device_id *id;
> +

> + id = acpi_match_device(upboard_acpi_match, dev);
> + if (!id)
> + return -ENODEV;
> +
> + switch (id->driver_data) {

device_get_match_data() IIRC the name of the call.

> + case UPBOARD_ID_UP2:
> + ddata->regmapconf = &upboard_up2_regmap_config;
> + ddata->cells = upboard_up2_mfd_cells;
> + ddata->ncells = ARRAY_SIZE(upboard_up2_mfd_cells);
> + break;
> + default:
> + dev_err(dev, "unsupported ID %lu\n", id->driver_data);
> + return -EINVAL;
> + }
> +
> + return 0;
> +}

> + ret = upboard_init_gpio(dev);
> + if (ret) {
> + if (ret != -EPROBE_DEFER)
> + dev_err(dev, "failed to init GPIOs: %d", ret);
> + return ret;
> + }

I don't know if probe_err() helper is going to be a part of v4.21
(which this series targets), it would be good to use it.

> +}

--
With Best Regards,
Andy Shevchenko

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