On Wed, Jun 15, 2022 at 08:37:45PM -0500, frank zago wrote:
> The GPIO interface offers 16 GPIOs. 6 are read/write, and 10 are
> read-only.
Please mention the single interrupt line here too.
> Signed-off-by: frank zago <frank@xxxxxxxx>
> ---
> MAINTAINERS | 1 +
> drivers/gpio/Kconfig | 10 +
> drivers/gpio/Makefile | 1 +
> drivers/gpio/gpio-ch341.c | 385 ++++++++++++++++++++++++++++++++++++++
> include/linux/mfd/ch341.h | 8 +
> 5 files changed, 405 insertions(+)
> create mode 100644 drivers/gpio/gpio-ch341.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 628eeaa9bf68..8b93f6192704 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -21479,6 +21479,7 @@ WINCHIPHEAD CH341 I2C/GPIO MFD DRIVER
> M: Frank Zago <frank@xxxxxxxx>
> L: linux-usb@xxxxxxxxxxxxxxx
> S: Maintained
> +F: drivers/gpio/gpio-ch341.c
> F: drivers/mfd/ch341-core.c
> F: include/linux/mfd/ch341.h
>
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index b01961999ced..473b6e7226ca 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -1653,6 +1653,16 @@ endmenu
> menu "USB GPIO expanders"
> depends on USB
>
> +config GPIO_CH341
> + tristate "CH341 USB to GPIO support"
> + select MFD_CH341
This should be "depends" (for all subdrivers).
> + help
> + If you say yes to this option, GPIO support will be included for the
> + WCH CH341, a USB to I2C/SPI/GPIO interface.
> +
> + This driver can also be built as a module. If so, the module
> + will be called gpio-ch341.
> +
> config GPIO_VIPERBOARD
> tristate "Viperboard GPIO a & b support"
> depends on MFD_VIPERBOARD
[ and other MFD drivers as you see here ]
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index 14352f6dfe8e..beef802cbfb1 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -44,6 +44,7 @@ obj-$(CONFIG_GPIO_BD9571MWV) += gpio-bd9571mwv.o
> obj-$(CONFIG_GPIO_BRCMSTB) += gpio-brcmstb.o
> obj-$(CONFIG_GPIO_BT8XX) += gpio-bt8xx.o
> obj-$(CONFIG_GPIO_CADENCE) += gpio-cadence.o
> +obj-$(CONFIG_GPIO_CH341) += gpio-ch341.o
> obj-$(CONFIG_GPIO_CLPS711X) += gpio-clps711x.o
> obj-$(CONFIG_GPIO_SNPS_CREG) += gpio-creg-snps.o
> obj-$(CONFIG_GPIO_CRYSTAL_COVE) += gpio-crystalcove.o
> diff --git a/drivers/gpio/gpio-ch341.c b/drivers/gpio/gpio-ch341.c
> new file mode 100644
> index 000000000000..233dfe1f2ae8
> --- /dev/null
> +++ b/drivers/gpio/gpio-ch341.c
> @@ -0,0 +1,385 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * GPIO cell driver for the CH341A and CH341B chips.
> + *
> + * Copyright 2022, Frank Zago
How about using a unified format for these lines?
> + * Copyright (c) 2017 Gunar Schorcht (gunar@xxxxxxxxxxxx)
> + * Copyright (c) 2016 Tse Lun Bien
> + * Copyright (c) 2014 Marco Gittler
> + * Copyright (c) 2006-2007 Till Harbaum (Till@xxxxxxxxxxx)
> + */
> +
> +/*
> + * Notes.
> + *
> + * For the CH341, 0=IN, 1=OUT, but for the GPIO subsystem, 1=IN and
> + * 0=OUT. Translation happens in a couple places.
> + */
> +
> +#include <linux/gpio/driver.h>
> +#include <linux/kernel.h>
> +#include <linux/mfd/ch341.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/types.h>
> +#include <linux/usb.h>
> +
> +#define CH341_GPIO_NUM_PINS 16 /* Number of GPIO pins */
> +
> +/* GPIO chip commands */
> +#define CH341_PARA_CMD_STS 0xA0 /* Get pins status */
> +#define CH341_CMD_UIO_STREAM 0xAB /* pin IO stream command */
> +
> +#define CH341_CMD_UIO_STM_OUT 0x80 /* pin IO interface OUT command (D0~D5) */
> +#define CH341_CMD_UIO_STM_DIR 0x40 /* pin IO interface DIR command (D0~D5) */
> +#define CH341_CMD_UIO_STM_END 0x20 /* pin IO interface END command */
> +
> +#define CH341_USB_MAX_INTR_SIZE 8
> +
> +struct ch341_gpio {
> + struct gpio_chip gpio;
> + struct mutex gpio_lock;
> + u16 gpio_dir; /* 1 bit per pin, 0=IN, 1=OUT. */
> + u16 gpio_last_read; /* last GPIO values read */
> + u16 gpio_last_written; /* last GPIO values written */
> + union {
> + u8 gpio_buf[SEG_SIZE];
> + __le16 gpio_buf_status;
> + };
This one should be allocated separately from the containing structure
since it may be mapped for DMA.
> +
> + struct urb *irq_urb;
> + struct usb_anchor irq_urb_out;
> + u8 irq_buf[CH341_USB_MAX_INTR_SIZE];
Same here.
You may need to check other drivers too.
> + struct irq_chip irq_chip;
> +
> + struct ch341_ddata *ddata;
> +};
> +
> +/*
> + * Masks to describe the 16 GPIOs. Pins D0 to D5 (mapped to GPIOs 0 to
> + * 5) can do input/output, but the other pins are input-only.
> + */
> +static const u16 pin_can_output = 0b111111;
> +
> +/* Only GPIO 10 (INT# line) has hardware interrupt */
> +#define CH341_GPIO_INT_LINE 10
> +
> +/* Send a command and get a reply if requested */
> +static int gpio_transfer(struct ch341_gpio *dev, int out_len, int in_len)
> +{
> + struct ch341_ddata *ddata = dev->ddata;
> + int actual;
> + int ret;
> +
> + mutex_lock(&ddata->usb_lock);
> +
> + ret = usb_bulk_msg(ddata->usb_dev,
> + usb_sndbulkpipe(ddata->usb_dev, ddata->ep_out),
> + dev->gpio_buf, out_len,
> + &actual, DEFAULT_TIMEOUT_MS);
> + if (ret < 0)
> + goto out_unlock;
> +
> + if (in_len == 0)
> + goto out_unlock;
> +
> + ret = usb_bulk_msg(ddata->usb_dev,
> + usb_rcvbulkpipe(ddata->usb_dev, ddata->ep_in),
> + dev->gpio_buf, SEG_SIZE, &actual, DEFAULT_TIMEOUT_MS);
> +
> +out_unlock:
> + mutex_unlock(&ddata->usb_lock);
> +
> + if (ret < 0)
> + return ret;
> +
> + return actual;
> +}
> +static void ch341_complete_intr_urb(struct urb *urb)
> +{
> + struct ch341_gpio *dev = urb->context;
> + int ret;
> +
> + if (urb->status) {
> + usb_unanchor_urb(dev->irq_urb);
Again, why is this here?
> + } else {
> + /*
> + * Data is 8 bytes. Byte 0 might be the length of
> + * significant data, which is 3 more bytes. Bytes 1
> + * and 2, and possibly 3, are the pin status. The byte
> + * order is different than for the GET_STATUS
> + * command. Byte 1 is GPIOs 8 to 15, and byte 2 is
> + * GPIOs 0 to 7.
> + */
> +
> + handle_nested_irq(irq_find_mapping(dev->gpio.irq.domain,
> + CH341_GPIO_INT_LINE));
> +
> + ret = usb_submit_urb(dev->irq_urb, GFP_ATOMIC);
> + if (ret)
> + usb_unanchor_urb(dev->irq_urb);
Ditto. This isn't how anchors are used.
> + }
> +}
> +
> +static int ch341_gpio_irq_set_type(struct irq_data *data, unsigned int flow_type)
> +{
> + const unsigned long offset = irqd_to_hwirq(data);
> +
> + if (offset != CH341_GPIO_INT_LINE || flow_type != IRQ_TYPE_EDGE_RISING)
> + return -EINVAL;
Ok, I missed this check before, sorry. So you do have a single interrupt
line.
You should probably add a comment in the enable() callback since this is
easy to miss.
> +
> + return 0;
> +}
> +
> +static void ch341_gpio_irq_enable(struct irq_data *data)
> +{
> + struct ch341_gpio *dev = irq_data_get_irq_chip_data(data);
> + int ret;
> +
> + /*
> + * The URB might have just been unlinked in
> + * ch341_gpio_irq_disable, but the completion handler hasn't
> + * been called yet.
> + */
> + if (!usb_wait_anchor_empty_timeout(&dev->irq_urb_out, 5000))
> + usb_kill_anchored_urbs(&dev->irq_urb_out);
You cannot sleep in this function.
> +
> + usb_anchor_urb(dev->irq_urb, &dev->irq_urb_out);
> + ret = usb_submit_urb(dev->irq_urb, GFP_KERNEL);
> + if (ret)
> + usb_unanchor_urb(dev->irq_urb);
> +}
> +
> +static void ch341_gpio_irq_disable(struct irq_data *data)
> +{
> + struct ch341_gpio *dev = irq_data_get_irq_chip_data(data);
> +
> + usb_unlink_urb(dev->irq_urb);
> +}
> +
> +static int ch341_gpio_remove(struct platform_device *pdev)
> +{
> + struct ch341_gpio *dev = platform_get_drvdata(pdev);
> +
> + usb_kill_anchored_urbs(&dev->irq_urb_out);
Again, this is racy as the gpio chip is still registered. And you don't
need an anchor to stop a single URB.
> + gpiochip_remove(&dev->gpio);
> + usb_free_urb(dev->irq_urb);
> +
> + return 0;
> +}
> +
> +static const struct irq_chip ch341_irqchip = {
> + .name = "CH341",
> + .irq_set_type = ch341_gpio_irq_set_type,
> + .irq_enable = ch341_gpio_irq_enable,
> + .irq_disable = ch341_gpio_irq_disable,
> + .flags = IRQCHIP_IMMUTABLE,
> + GPIOCHIP_IRQ_RESOURCE_HELPERS,
> +};
> +
> +static int ch341_gpio_probe(struct platform_device *pdev)
> +{
> + struct ch341_ddata *ddata = dev_get_drvdata(pdev->dev.parent);
> + struct gpio_irq_chip *girq;
> + struct ch341_gpio *dev;
> + struct gpio_chip *gpio;
> + int ret;
> +
> + dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
> + if (dev == NULL)
> + return -ENOMEM;
> +
> + platform_set_drvdata(pdev, dev);
> + dev->ddata = ddata;
> + mutex_init(&dev->gpio_lock);
> +
> + gpio = &dev->gpio;
> + gpio->label = dev_name(&pdev->dev);
> + gpio->parent = &pdev->dev;
> + gpio->owner = THIS_MODULE;
> + gpio->get_direction = ch341_gpio_get_direction;
> + gpio->direction_input = ch341_gpio_direction_input;
> + gpio->direction_output = ch341_gpio_direction_output;
> + gpio->get = ch341_gpio_get;
> + gpio->get_multiple = ch341_gpio_get_multiple;
> + gpio->set = ch341_gpio_set;
> + gpio->set_multiple = ch341_gpio_set_multiple;
> + gpio->base = -1;
> + gpio->ngpio = CH341_GPIO_NUM_PINS;
> + gpio->can_sleep = true;
> +
> + girq = &gpio->irq;
> + gpio_irq_chip_set_chip(girq, &ch341_irqchip);
> + girq->handler = handle_simple_irq;
> + girq->default_type = IRQ_TYPE_NONE;
> +
> + /* Create an URB for handling interrupt */
> + dev->irq_urb = usb_alloc_urb(0, GFP_KERNEL);
> + if (!dev->irq_urb)
> + return dev_err_probe(&pdev->dev, -ENOMEM, "Cannot allocate the int URB\n");
This isn't how dev_err_probe() is used.
And allocation failures are already logged so just return -ENOMEM here.
> +
> + usb_fill_int_urb(dev->irq_urb, ddata->usb_dev,
> + usb_rcvintpipe(ddata->usb_dev, ddata->ep_intr),
> + dev->irq_buf, CH341_USB_MAX_INTR_SIZE,
> + ch341_complete_intr_urb, dev, ddata->ep_intr_interval);
> +
> + init_usb_anchor(&dev->irq_urb_out);
> +
> + ret = gpiochip_add_data(gpio, dev);
> + if (ret) {
> + ret = dev_err_probe(&pdev->dev, ret, "Could not add GPIO\n");
> + goto release_urb;
> + }
> +
> + return 0;
> +
> +release_urb:
> + usb_free_urb(dev->irq_urb);
> +
> + return ret;
> +}
Johan
