Hi Johannes,
On Fri, Jun 23, 2023 at 01:01:45PM +0200, Johannes Roith wrote:
> Added a gpiochip compatible driver to control the 8 GPIOs of the MCP2200
> by using the HID interface.
>
> Using GPIOs with alternative functions (GP0<->SSPND, GP1<->USBCFG,
> GP6<->RXLED, GP7<->TXLED) will reset the functions, if set (unset by
> default).
>
> The driver was tested while also using the UART of the chip. Setting
> and reading the GPIOs has no effect on the UART communication. However,
> a reset is triggered after the CONFIGURE command. If the GPIO Direction
> is constantly changed, this will affect the communication at low baud
> rates. This is a hardware problem of the MCP2200 and is not caused by
> the driver.
>
> Feedback from reviewers Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
> and Andi Shyti <andi.shyti@xxxxxxxxxx> was added.
>
> Signed-off-by: Johannes Roith <johannes@gnu-linux.rocks>
Just one note... please add a versioning to your patches and a
changelog.
I saw that your previous version did not receive any reply
(sorry)... in that case you could add a prefix RESEND.
So that this patch would look like:
[PATCH RESEND v3] hid-mcp2200: Added driver for GPIOs of MCP2200
(note "Added" with capital letter)
[...]
> +/* Altternative pin assignments */
Alternative
> +#define TXLED 2
> +#define RXLED 3
> +#define USBCFG 6
> +#define SSPND 7
> +#define MCP_NGPIO 8
[...]
> +static int mcp_cmd_read_all(struct mcp2200 *mcp)
> +{
> + struct mcp_read_all *read_all;
> + int len, t;
> +
> + reinit_completion(&mcp->wait_in_report);
> + read_all = kzalloc(sizeof(struct mcp_read_all), GFP_KERNEL);
> + if (!read_all)
> + return -ENOMEM;
any reason for allocating read_all dynamically?
> +
> + read_all->cmd = READ_ALL;
> +
> + mutex_lock(&mcp->lock);
> + len = hid_hw_output_report(mcp->hdev, (u8 *) read_all,
> + sizeof(struct mcp_read_all));
Please align "sizeof" with "mcp"
> + mutex_unlock(&mcp->lock);
> + kfree(read_all);
> +
> + if (len != sizeof(struct mcp_read_all))
> + return -EINVAL;
> +
> + t = wait_for_completion_timeout(&mcp->wait_in_report, msecs_to_jiffies(4000));
not an error, just a suggestion... would be nice to keep lines
withing 80 characters whenever possible... and here it's possible :)
> + if (!t)
> + return -ETIMEDOUT;
> +
> + /* return status, negative value if wrong response was received */
> + return mcp->status;
> +}
> +
> +static void mcp_set_multiple(struct gpio_chip *gc, unsigned long *mask,
> + unsigned long *bits)
please align "struct" with "unsigned"
> +{
> + struct mcp2200 *mcp = gpiochip_get_data(gc);
> + u8 value;
> + int status;
> + struct mcp_set_clear_outputs *cmd;
> +
> + cmd = kzalloc(sizeof(struct mcp_set_clear_outputs), GFP_KERNEL);
> + if (!cmd)
> + return;
> +
> + mutex_lock(&mcp->lock);
> +
> + value = mcp->gpio_val & ~*mask;
> + value |= (*mask & *bits);
> +
> + cmd->cmd = SET_CLEAR_OUTPUTS;
> + cmd->set_bmap = value;
> + cmd->clear_bmap = ~(value);
> +
> + status = hid_hw_output_report(mcp->hdev, (u8 *) cmd,
> + sizeof(struct mcp_set_clear_outputs));
> +
> + mutex_unlock(&mcp->lock);
> + kfree(cmd);
again, any reason for allocating dynamically cmd?
> + if (status == sizeof(struct mcp_set_clear_outputs))
> + mcp->gpio_val = value;
should this be inside the lock?
> +}
[...]
> +static int mcp_get(struct gpio_chip *gc, unsigned int gpio_nr)
> +{
> + unsigned long mask = 0, bits = 0;
> +
> + mask = (1 << gpio_nr);
> + mcp_get_multiple(gc, &mask, &bits);
> + return (bits > 0) ? 1 : 0;
eventually you could just:
return bits > 0;
> +}
[...]
> +static int mcp2200_probe(struct hid_device *hdev, const struct hid_device_id *id)
> +{
> + int ret;
> + struct mcp2200 *mcp;
> +
> + mcp = devm_kzalloc(&hdev->dev, sizeof(*mcp), GFP_KERNEL);
> + if (!mcp)
> + return -ENOMEM;
> +
> + ret = hid_parse(hdev);
> + if (ret) {
> + hid_err(hdev, "can't parse reports\n");
> + return ret;
Is it dev_err_probe() preferred to hid_err() here?
> + }
> +
> + /*
> + * This driver uses the .raw_event callback and therefore does not need any
> + * HID_CONNECT_xxx flags.
> + */
> + ret = hid_hw_start(hdev, 0);
> + if (ret) {
> + hid_err(hdev, "can't start hardware\n");
> + return ret;
> + }
> +
> + hid_info(hdev, "USB HID v%x.%02x Device [%s] on %s\n", hdev->version >> 8,
> + hdev->version & 0xff, hdev->name, hdev->phys);
> +
> + ret = hid_hw_open(hdev);
> + if (ret) {
> + hid_err(hdev, "can't open device\n");
> + hid_hw_stop(hdev);
> + return ret;
> + }
> +
> + mutex_init(&mcp->lock);
> + init_completion(&mcp->wait_in_report);
> + hid_set_drvdata(hdev, mcp);
> + mcp->hdev = hdev;
> +
> + ret = devm_add_action_or_reset(&hdev->dev, mcp2200_hid_unregister, hdev);
> + if (ret)
hit_hw_stop()?
Maybe a goto is better?
Andi
> + return ret;
> +
> + mcp->gc = template_chip;
> + mcp->gc.parent = &hdev->dev;
> +
> + ret = gpiochip_add_data(&mcp->gc, mcp);
> + if (ret < 0) {
> + dev_err(&hdev->dev, "Unable to register gpiochip\n");
> + hid_hw_stop(hdev);
> + return ret;
> + }
> +
> + return 0;
> +}
