On Thu, Sep 26, 2024 at 2:44 PM Mary Strodl <mstrodl@xxxxxxxxxxx> wrote:
>
> FTDI FT2232H is a USB to GPIO chip. Sealevel produces some devices
> with this chip. FT2232H presents itself as a composite device with two
> interfaces (each is an "MPSSE"). Each MPSSE has two banks (high and low)
> of 8 GPIO each. I believe some MPSSE's have only one bank, but I don't
> know how to identify them (I don't have any for testing) and as a result
> are unsupported for the time being.
>
> Additionally, this driver provides software polling-based interrupts for
> edge detection. For the Sealevel device I have to test with, this works
> well because there is hardware debouncing. From talking to Sealevel's
> people, this is their preferred way to do edge detection.
>
> Signed-off-by: Mary Strodl <mstrodl@xxxxxxxxxxx>
> ---
>
> Changes since last time:
> * Switch to linux/cleanup.h mutex guards
> * Use defines for GPIO_LINE_DIRECTION
> * Skip the polling loop if get_multiple fails
> * Remove unneeded `irq_domain_remove` call, it's no longer managed externally
>
> drivers/gpio/Kconfig | 7 +
> drivers/gpio/Makefile | 1 +
> drivers/gpio/gpio-mpsse.c | 522 ++++++++++++++++++++++++++++++++++++++
> 3 files changed, 530 insertions(+)
> create mode 100644 drivers/gpio/gpio-mpsse.c
>
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index d93cd4f722b4..cbe3baa1b3de 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -1844,6 +1844,13 @@ config GPIO_VIPERBOARD
> River Tech's viperboard.h for detailed meaning
> of the module parameters.
>
> +config GPIO_MPSSE
> + tristate "FTDI MPSSE GPIO support"
> + select GPIOLIB_IRQCHIP
> + help
> + GPIO driver for FTDI's MPSSE interface. These can do input and
> + output. Each MPSSE provides 16 IO pins.
> +
> endmenu
>
> menu "Virtual GPIO drivers"
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index 1429e8c0229b..cc5d5519ba4b 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -114,6 +114,7 @@ obj-$(CONFIG_GPIO_MOCKUP) += gpio-mockup.o
> obj-$(CONFIG_GPIO_MOXTET) += gpio-moxtet.o
> obj-$(CONFIG_GPIO_MPC5200) += gpio-mpc5200.o
> obj-$(CONFIG_GPIO_MPC8XXX) += gpio-mpc8xxx.o
> +obj-$(CONFIG_GPIO_MPSSE) += gpio-mpsse.o
> obj-$(CONFIG_GPIO_MSC313) += gpio-msc313.o
> obj-$(CONFIG_GPIO_MT7621) += gpio-mt7621.o
> obj-$(CONFIG_GPIO_MVEBU) += gpio-mvebu.o
> diff --git a/drivers/gpio/gpio-mpsse.c b/drivers/gpio/gpio-mpsse.c
> new file mode 100644
> index 000000000000..cf63178135c7
> --- /dev/null
> +++ b/drivers/gpio/gpio-mpsse.c
> @@ -0,0 +1,522 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * FTDI MPSSE GPIO support
> + *
> + * Based on code by Anatolij Gustschin
> + *
> + * Copyright (C) 2024 Mary Strodl <mstrodl@xxxxxxxxxxx>
> + */
> +
> +#include <linux/cleanup.h>
> +#include <linux/gpio/driver.h>
> +#include <linux/mutex.h>
> +#include <linux/usb.h>
> +
> +struct mpsse_priv {
> + struct gpio_chip gpio;
> + struct usb_device *udev; /* USB device encompassing all MPSSEs */
> + struct usb_interface *intf; /* USB interface for this MPSSE */
> + u8 intf_id; /* USB interface number for this MPSSE */
> + struct work_struct irq_work; /* polling work thread */
> + struct mutex irq_mutex; /* lock over irq_data */
> + atomic_t irq_type[16]; /* pin -> edge detection type */
> + atomic_t irq_enabled;
> + int id;
> +
> + u8 gpio_outputs[2]; /* Output states for GPIOs [L, H] */
> + u8 gpio_dir[2]; /* Directions for GPIOs [L, H] */
> +
> + u8 *bulk_in_buf; /* Extra recv buffer to grab status bytes */
> +
> + struct usb_endpoint_descriptor *bulk_in;
> + struct usb_endpoint_descriptor *bulk_out;
> +
> + struct mutex io_mutex; /* sync I/O with disconnect */
> +};
> +
> +struct bulk_desc {
> + bool tx; /* direction of bulk transfer */
> + u8 *data; /* input (tx) or output (rx) */
> + int len; /* Length of `data` if tx, or length of */
> + /* Data to read if rx */
> + int len_actual; /* Length successfully transferred */
> + int timeout;
> +};
> +
> +static const struct usb_device_id gpio_mpsse_table[] = {
> + { USB_DEVICE(0x0c52, 0xa064) }, /* SeaLevel Systems, Inc. */
> + { } /* Terminating entry */
> +};
I don't know much about the USB subsystem in the kernel, maybe Cc Greg
KH on this?
> +
> +MODULE_DEVICE_TABLE(usb, gpio_mpsse_table);
> +
> +static DEFINE_IDA(gpio_mpsse_ida);
> +
> +/* MPSSE commands */
> +#define SET_BITS_CMD 0x80
> +#define GET_BITS_CMD 0x81
> +
> +#define SET_BITMODE_REQUEST 0x0B
> +#define MODE_MPSSE (2 << 8)
> +#define MODE_RESET 0
> +
> +/* Arbitrarily decided. This could probably be much less */
> +#define MPSSE_WRITE_TIMEOUT 5000
> +#define MPSSE_READ_TIMEOUT 5000
> +
> +/* 1 millisecond, also pretty arbitrary */
> +#define MPSSE_POLL_INTERVAL 1000
> +
> +static int mpsse_bulk_xfer(struct usb_interface *intf, struct bulk_desc *desc)
> +{
> + struct mpsse_priv *priv = usb_get_intfdata(intf);
> + struct usb_device *udev = priv->udev;
> + unsigned int pipe;
> + int ret;
> +
> + if (desc->tx)
> + pipe = usb_sndbulkpipe(udev, priv->bulk_out->bEndpointAddress);
> + else
> + pipe = usb_rcvbulkpipe(udev, priv->bulk_in->bEndpointAddress);
> +
> + ret = usb_bulk_msg(udev, pipe, desc->data, desc->len,
> + &desc->len_actual, desc->timeout);
> + if (ret)
> + dev_dbg(&udev->dev, "mpsse: bulk transfer failed: %d\n", ret);
> +
> + return ret;
> +}
> +
> +static int mpsse_write(struct usb_interface *intf,
> + u8 *buf, size_t len)
> +{
> + int ret;
> + struct bulk_desc desc;
> +
> + desc.len_actual = 0;
> + desc.tx = true;
> + desc.data = buf;
> + desc.len = len;
> + desc.timeout = MPSSE_WRITE_TIMEOUT;
> +
> + ret = mpsse_bulk_xfer(intf, &desc);
> +
> + return ret;
> +}
> +
> +static int mpsse_read(struct usb_interface *intf, u8 *buf, size_t len)
> +{
> + int ret;
> + struct bulk_desc desc;
> + struct mpsse_priv *priv = usb_get_intfdata(intf);
> +
> + desc.len_actual = 0;
> + desc.tx = false;
> + desc.data = priv->bulk_in_buf;
> + /* Device sends 2 additional status bytes, read len + 2 */
> + desc.len = min_t(size_t, len + 2, usb_endpoint_maxp(priv->bulk_in));
> + desc.timeout = MPSSE_READ_TIMEOUT;
> +
> + ret = mpsse_bulk_xfer(intf, &desc);
> + if (ret)
> + return ret;
> +
> + /* Did we get enough data? */
> + if (desc.len_actual < desc.len)
> + return -EIO;
> +
> + memcpy(buf, desc.data + 2, desc.len_actual - 2);
> +
> + return ret;
> +}
> +
> +static int gpio_mpsse_set_bank(struct mpsse_priv *priv, u8 bank)
> +{
> + int ret;
> + u8 tx_buf[3] = {
> + SET_BITS_CMD | (bank << 1),
> + priv->gpio_outputs[bank],
> + priv->gpio_dir[bank],
> + };
> +
> + ret = mpsse_write(priv->intf, tx_buf, 3);
> +
> + return ret;
> +}
> +
> +static int gpio_mpsse_get_bank(struct mpsse_priv *priv, u8 bank)
> +{
> + int ret;
> + u8 buf = GET_BITS_CMD | (bank << 1);
> +
> + ret = mpsse_write(priv->intf, &buf, 1);
> + if (ret)
> + return ret;
> +
> + ret = mpsse_read(priv->intf, &buf, 1);
> + if (ret)
> + return ret;
> +
> + return buf;
> +}
> +
> +static void gpio_mpsse_set_multiple(struct gpio_chip *chip, unsigned long *mask,
> + unsigned long *bits)
> +{
> + unsigned long i, bank, bank_mask, bank_bits;
> + int ret;
> + struct mpsse_priv *priv = gpiochip_get_data(chip);
> +
> + guard(mutex)(&priv->io_mutex);
> + for_each_set_clump8(i, bank_mask, mask, chip->ngpio) {
> + bank = i / 8;
> +
> + if (bank_mask) {
> + bank_bits = bitmap_get_value8(bits, i);
> + /* Zero out pins we want to change */
> + priv->gpio_outputs[bank] &= ~bank_mask;
> + /* Set pins we care about */
> + priv->gpio_outputs[bank] |= bank_bits & bank_mask;
> +
> + ret = gpio_mpsse_set_bank(priv, bank);
> + if (ret)
> + dev_err(&priv->intf->dev,
> + "Couldn't set values for bank %ld!",
> + bank);
> + }
> + }
> +}
> +
> +static int gpio_mpsse_get_multiple(struct gpio_chip *chip, unsigned long *mask,
> + unsigned long *bits)
> +{
> + unsigned long i, bank, bank_mask;
> + int ret;
> + struct mpsse_priv *priv = gpiochip_get_data(chip);
> +
> + guard(mutex)(&priv->io_mutex);
> + for_each_set_clump8(i, bank_mask, mask, chip->ngpio) {
> + bank = i / 8;
> +
> + if (bank_mask) {
> + ret = gpio_mpsse_get_bank(priv, bank);
> + if (ret < 0)
> + return ret;
> +
> + bitmap_set_value8(bits, ret & bank_mask, i);
> + }
> + }
> +
> + return 0;
> +}
> +
> +static int gpio_mpsse_gpio_get(struct gpio_chip *chip, unsigned int offset)
> +{
> + int err;
> + unsigned long mask = 0, bits = 0;
> +
> + __set_bit(offset, &mask);
> + err = gpio_mpsse_get_multiple(chip, &mask, &bits);
> + if (err)
> + return err;
> +
> + /* == is not guaranteed to give 1 if true */
> + if (bits)
> + return 1;
> + else
> + return 0;
> +}
> +
> +static void gpio_mpsse_gpio_set(struct gpio_chip *chip, unsigned int offset,
> + int value)
> +{
> + unsigned long mask = 0, bits = 0;
> +
> + __set_bit(offset, &mask);
> + if (value)
> + __set_bit(offset, &bits);
> +
> + gpio_mpsse_set_multiple(chip, &mask, &bits);
> +}
> +
> +static int gpio_mpsse_direction_output(struct gpio_chip *chip,
> + unsigned int offset, int value)
> +{
> + struct mpsse_priv *priv = gpiochip_get_data(chip);
> + int bank = (offset & 8) >> 3;
> + int bank_offset = offset & 7;
> +
> + scoped_guard(mutex, &priv->io_mutex)
> + priv->gpio_dir[bank] |= BIT(bank_offset);
Add a newline here.
> + gpio_mpsse_gpio_set(chip, offset, value);
> +
> + return 0;
> +}
> +
> +static int gpio_mpsse_direction_input(struct gpio_chip *chip,
> + unsigned int offset)
> +{
> + struct mpsse_priv *priv = gpiochip_get_data(chip);
> + int bank = (offset & 8) >> 3;
> + int bank_offset = offset & 7;
> +
> + guard(mutex)(&priv->io_mutex);
> + priv->gpio_dir[bank] &= ~BIT(bank_offset);
> + gpio_mpsse_set_bank(priv, bank);
> +
> + return 0;
> +}
> +
> +static int gpio_mpsse_get_direction(struct gpio_chip *chip,
> + unsigned int offset)
> +{
> + int ret;
> + int bank = (offset & 8) >> 3;
> + int bank_offset = offset & 7;
> + struct mpsse_priv *priv = gpiochip_get_data(chip);
> +
> + guard(mutex)(&priv->io_mutex);
> + /* MPSSE directions are inverted */
> + if (priv->gpio_dir[bank] & BIT(bank_offset))
> + ret = GPIO_LINE_DIRECTION_OUT;
> + else
> + ret = GPIO_LINE_DIRECTION_IN;
> +
> + return ret;
> +}
> +
> +static void gpio_mpsse_poll(struct work_struct *work)
> +{
> + unsigned long pin_mask, pin_states, flags;
> + int irq_enabled, offset, err, value, fire_irq,
> + irq, old_value[16], irq_type[16];
> + struct mpsse_priv *priv = container_of(work, struct mpsse_priv,
> + irq_work);
> +
> + for (offset = 0; offset < priv->gpio.ngpio; ++offset)
> + old_value[offset] = -1;
> +
> + while ((irq_enabled = atomic_read(&priv->irq_enabled))) {
> + usleep_range(MPSSE_POLL_INTERVAL, MPSSE_POLL_INTERVAL + 1000);
> + /* Cleanup will trigger at the end of the loop */
> + guard(mutex)(&priv->irq_mutex);
> +
> + pin_mask = 0;
> + pin_states = 0;
> + for (offset = 0; offset < priv->gpio.ngpio; ++offset) {
> + irq_type[offset] = atomic_read(&priv->irq_type[offset]);
> + if (irq_type[offset] != IRQ_TYPE_NONE &&
> + irq_enabled & BIT(offset))
> + pin_mask |= BIT(offset);
> + else
> + old_value[offset] = -1;
> + }
> +
> + err = gpio_mpsse_get_multiple(&priv->gpio, &pin_mask,
> + &pin_states);
> + if (err) {
> + dev_err_ratelimited(&priv->intf->dev,
> + "Error polling!\n");
> + continue;
> + }
> +
> + /* Check each value */
> + for (offset = 0; offset < priv->gpio.ngpio; ++offset) {
> + if (old_value[offset] == -1)
> + continue;
> +
> + fire_irq = 0;
> + value = pin_states & BIT(offset);
> +
> + switch (irq_type[offset]) {
> + case IRQ_TYPE_EDGE_RISING:
> + fire_irq = value > old_value[offset];
> + break;
> + case IRQ_TYPE_EDGE_FALLING:
> + fire_irq = value < old_value[offset];
> + break;
> + case IRQ_TYPE_EDGE_BOTH:
> + fire_irq = value != old_value[offset];
> + break;
> + }
> + if (!fire_irq)
> + continue;
> +
> + irq = irq_find_mapping(priv->gpio.irq.domain,
> + offset);
> + local_irq_save(flags);
> + generic_handle_irq(irq);
> + local_irq_disable();
> + local_irq_restore(flags);
> + }
> +
> + /* Sync back values so we can refer to them next tick */
> + for (offset = 0; offset < priv->gpio.ngpio; ++offset)
> + if (irq_type[offset] != IRQ_TYPE_NONE &&
> + irq_enabled & BIT(offset))
> + old_value[offset] = pin_states & BIT(offset);
> + }
> +}
> +
> +static int gpio_mpsse_set_irq_type(struct irq_data *irqd, unsigned int type)
> +{
> + int offset;
> + struct mpsse_priv *priv = irq_data_get_irq_chip_data(irqd);
> +
> + offset = irqd->hwirq;
> + atomic_set(&priv->irq_type[offset], type & IRQ_TYPE_EDGE_BOTH);
> +
> + return 0;
> +}
> +
> +static void gpio_mpsse_irq_disable(struct irq_data *irqd)
> +{
> + struct mpsse_priv *priv = irq_data_get_irq_chip_data(irqd);
> +
> + atomic_and(~BIT(irqd->hwirq), &priv->irq_enabled);
> + gpiochip_disable_irq(&priv->gpio, irqd->hwirq);
> +}
> +
> +static void gpio_mpsse_irq_enable(struct irq_data *irqd)
> +{
> + struct mpsse_priv *priv = irq_data_get_irq_chip_data(irqd);
> +
> + gpiochip_enable_irq(&priv->gpio, irqd->hwirq);
> + /* If no-one else was using the IRQ, enable it */
> + if (!atomic_fetch_or(BIT(irqd->hwirq), &priv->irq_enabled)) {
> + INIT_WORK(&priv->irq_work, gpio_mpsse_poll);
> + schedule_work(&priv->irq_work);
> + }
> +}
> +
> +static const struct irq_chip gpio_mpsse_irq_chip = {
> + .name = "gpio-mpsse-irq",
> + .irq_enable = gpio_mpsse_irq_enable,
> + .irq_disable = gpio_mpsse_irq_disable,
> + .irq_set_type = gpio_mpsse_set_irq_type,
> + .flags = IRQCHIP_IMMUTABLE,
> + GPIOCHIP_IRQ_RESOURCE_HELPERS,
> +};
> +
> +static int gpio_mpsse_probe(struct usb_interface *interface,
> + const struct usb_device_id *id)
> +{
> + struct mpsse_priv *priv;
> + struct device *dev;
> + int err;
> +
> + dev = &interface->dev;
> + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> + if (!priv)
> + return -ENOMEM;
> +
> + priv->udev = usb_get_dev(interface_to_usbdev(interface));
> + priv->intf = interface;
> + priv->intf_id = interface->cur_altsetting->desc.bInterfaceNumber;
> +
> + priv->id = ida_simple_get(&gpio_mpsse_ida, 0, 0, GFP_KERNEL);
> + if (priv->id < 0)
> + return priv->id;
> +
> + devm_mutex_init(dev, &priv->io_mutex);
> + devm_mutex_init(dev, &priv->irq_mutex);
> +
> + priv->gpio.label = devm_kasprintf(dev, GFP_KERNEL,
> + "gpio-mpsse.%d.%d",
> + priv->id, priv->intf_id);
> + if (!priv->gpio.label) {
> + err = -ENOMEM;
> + goto err;
> + }
> +
> + priv->gpio.owner = THIS_MODULE;
> + priv->gpio.parent = interface->usb_dev;
> + priv->gpio.get_direction = gpio_mpsse_get_direction;
> + priv->gpio.direction_input = gpio_mpsse_direction_input;
> + priv->gpio.direction_output = gpio_mpsse_direction_output;
> + priv->gpio.get = gpio_mpsse_gpio_get;
> + priv->gpio.set = gpio_mpsse_gpio_set;
> + priv->gpio.get_multiple = gpio_mpsse_get_multiple;
> + priv->gpio.set_multiple = gpio_mpsse_set_multiple;
> + priv->gpio.base = -1;
> + priv->gpio.ngpio = 16;
> + priv->gpio.offset = priv->intf_id * priv->gpio.ngpio;
> + priv->gpio.can_sleep = 1;
> +
> + err = usb_find_common_endpoints(interface->cur_altsetting,
> + &priv->bulk_in, &priv->bulk_out,
> + NULL, NULL);
> + if (err)
> + goto err;
> +
> + priv->bulk_in_buf = devm_kmalloc(dev, usb_endpoint_maxp(priv->bulk_in),
> + GFP_KERNEL);
> + if (!priv->bulk_in_buf) {
> + err = -ENOMEM;
> + goto err;
> + }
> +
> + usb_set_intfdata(interface, priv);
> +
Stray newline
> +
> + /* Reset mode, needed to correctly enter MPSSE mode */
> + err = usb_control_msg(priv->udev, usb_sndctrlpipe(priv->udev, 0),
> + SET_BITMODE_REQUEST,
> + USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
> + MODE_RESET, priv->intf_id + 1, NULL, 0,
> + USB_CTRL_SET_TIMEOUT);
> + if (err)
> + goto err;
> +
> + /* Enter MPSSE mode */
> + err = usb_control_msg(priv->udev, usb_sndctrlpipe(priv->udev, 0),
> + SET_BITMODE_REQUEST,
> + USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
> + MODE_MPSSE, priv->intf_id + 1, NULL, 0,
> + USB_CTRL_SET_TIMEOUT);
> + if (err)
> + goto err;
> +
> + gpio_irq_chip_set_chip(&priv->gpio.irq, &gpio_mpsse_irq_chip);
> +
> + priv->gpio.irq.parent_handler = NULL;
> + priv->gpio.irq.num_parents = 0;
> + priv->gpio.irq.parents = NULL;
> + priv->gpio.irq.default_type = IRQ_TYPE_NONE;
> + priv->gpio.irq.handler = handle_simple_irq;
> +
> + err = devm_gpiochip_add_data(dev, &priv->gpio, priv);
> + if (err)
> + goto err;
> +
> + return 0;
> +
> +err:
> + ida_simple_remove(&gpio_mpsse_ida, priv->id);
> +
You could drop this label, all the gotos and the corresponding free in
remove if you scheduled a devm action with devm_add_action_or_reset()
right after getting the new index.
> + return err;
> +}
> +
> +static void gpio_mpsse_disconnect(struct usb_interface *intf)
> +{
> + struct mpsse_priv *priv = usb_get_intfdata(intf);
> +
> + ida_simple_remove(&gpio_mpsse_ida, priv->id);
> +
> + priv->intf = NULL;
> + usb_set_intfdata(intf, NULL);
> + usb_put_dev(priv->udev);
> +}
> +
> +static struct usb_driver gpio_mpsse_driver = {
> + .name = "gpio-mpsse",
> + .probe = gpio_mpsse_probe,
> + .disconnect = gpio_mpsse_disconnect,
> + .id_table = gpio_mpsse_table,
> +};
> +
> +module_usb_driver(gpio_mpsse_driver);
> +
> +MODULE_AUTHOR("Mary Strodl <mstrodl@xxxxxxxxxxx>");
> +MODULE_DESCRIPTION("MPSSE GPIO driver");
> +MODULE_LICENSE("GPL");
> --
> 2.45.2
>
Overall it looks clean and nice but I can't tell if the USB-specific
bits are correct.
Bart
Re: [PATCH v3] gpio: add support for FTDI's MPSSE as GPIO
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- Subject: Re: [PATCH v3] gpio: add support for FTDI's MPSSE as GPIO
- From: Bartosz Golaszewski <brgl@xxxxxxxx>
- Date: Tue, 1 Oct 2024 21:04:58 +0200
- In-reply-to: <20240926124424.2133464-1-mstrodl@csh.rit.edu>
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