>Le 11/06/2023 à 18:48, Johannes Roith a écrit : >> 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. >> >> Signed-off-by: Johannes Roith <johannes@gnu-linux.rocks> > >Hi, > >a few nits below, should it help the review. > >[...] > >> --- /dev/null >> +++ b/drivers/hid/hid-mcp2200.c >> @@ -0,0 +1,421 @@ >> +// SPDX-License-Identifier: GPL-2.0-only >> +/* >> + * MCP2200 - Microchip USB to GPIO bridge >> + * >> + * Copyright (c) 2023, Johannes Roith <johannes@gnu-linux.rocks> >> + * >> + * Datasheet: https://ww1.microchip.com/downloads/en/DeviceDoc/22228A.pdf >> + * App Note for HID: https://ww1.microchip.com/downloads/en/DeviceDoc/93066A.pdf >> + */ >> +#include <linux/module.h> >> +#include <linux/err.h> >> +#include <linux/mutex.h> >> +#include <linux/bitfield.h> > >Is this include needed? > >> +#include <linux/completion.h> >> +#include <linux/delay.h> >> +#include <linux/hid.h> >> +#include <linux/hidraw.h> >> +#include <linux/gpio/driver.h> > >Many maintainers prefer alphabetic order for includes. > > >> +#include "hid-ids.h" >> + >> +/* Commands codes in a raw output report */ >> +enum { >> + SET_CLEAR_OUTPUTS = 0x08, >> + CONFIGURE = 0x10, >> + READ_EE = 0x20, >> + WRITE_EE = 0x40, >> + READ_ALL = 0x80 >> +}; > >Does some > #define xxx BIT(n) >would make more sense than this enum? I have changed the enum to defines. But I kept the hexadecimal format as the commands comes from the HID appnote and I think it is more readable that way. > >> + >> +/* MCP GPIO direction encoding */ >> +enum MCP_IO_DIR { >> + MCP2200_DIR_OUT = 0x00, >> + MCP2200_DIR_IN = 0x01, >> +}; >> + >> +/* Altternative pin assignments */ >> +enum { >> + TXLED = 2, >> + RXLED = 3, >> + USBCFG = 6, >> + SSPND = 7, >> + > >Uneeded new line. > >> +}; >> + >> +#define MCP_NGPIO 8 >> + > >[...] > >> +/* this executes the READ_ALL cmd */ >> +static int mcp_cmd_read_all(struct mcp2200 *mcp) >> +{ >> + struct mcp_read_all *read_all; >> + int len, t; >> + >> + reinit_completion(&mcp->wait_in_report); >> + mutex_lock(&mcp->lock); >> + >> + read_all = kzalloc(sizeof(struct mcp_read_all), GFP_KERNEL); >> + if (!read_all) >> + return -ENOMEM; > >Allocation could be deone before the lock. > >> + >> + read_all->cmd = READ_ALL; >> + len = hid_hw_output_report(mcp->hdev, (u8 *) read_all, >> + sizeof(struct mcp_read_all)); >> + >> + if (len != sizeof(struct mcp_read_all)) > >kfree(read_all); ? >(or move the call just below before the test) > >> + return -EINVAL; >> + >> + kfree(read_all); >> + mutex_unlock(&mcp->lock); > >Mutex unlock could be done before kfree() or even before the "if >(len..." a few lines above. > >> + t = wait_for_completion_timeout(&mcp->wait_in_report, msecs_to_jiffies(4000)); >> + 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) >> +{ >> + 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)); >> + if (status == sizeof(struct mcp_set_clear_outputs)) >> + mcp->gpio_val = value; >> + >> + kfree(cmd); >> + mutex_unlock(&mcp->lock); > >Mutex unlock could be done before kfree(). > >> +} >> + >> +static void mcp_set(struct gpio_chip *gc, unsigned int gpio_nr, int value) >> +{ >> + unsigned long mask = (1 << gpio_nr); > >Uneeded () >Does using BIT makes sense here? > >> + unsigned long bmap_value = (value<<gpio_nr); > >Uneeded () and missing spaces aoud << > >> + >> + mcp_set_multiple(gc, &mask, &bmap_value); >> +} >> + >> +static int mcp_get_multiple(struct gpio_chip *gc, unsigned long *mask, >> + unsigned long *bits) >> +{ >> + u32 val; >> + struct mcp2200 *mcp = gpiochip_get_data(gc); >> + int status; >> + >> + status = mcp_cmd_read_all(mcp); >> + if (status != 0) >> + return status; >> + >> + val = mcp->gpio_inval; >> + *bits = (val & *mask); >> + return 0; >> +} >> + >> +static int mcp_get(struct gpio_chip *gc, unsigned int gpio_nr) >> +{ >> + unsigned long mask = 0, bits = 0; > >No need to init long (and maybe bits) > >> + >> + mask = (1 << gpio_nr); > >Uneeded () >Does using BIT makes sense here? > >> + mcp_get_multiple(gc, &mask, &bits); >> + return (bits > 0) ? 1 : 0; >> +} >> + >> +static int mcp_get_direction(struct gpio_chip *gc, unsigned int gpio_nr) >> +{ >> + struct mcp2200 *mcp = gpiochip_get_data(gc); >> + >> + return (mcp->gpio_dir & (MCP2200_DIR_IN << gpio_nr)) >> + ? GPIO_LINE_DIRECTION_IN : GPIO_LINE_DIRECTION_OUT; >> +} >> + >> +static int mcp_set_direction(struct gpio_chip *gc, unsigned int gpio_nr, >> + enum MCP_IO_DIR io_direction) >> +{ >> + struct mcp2200 *mcp = gpiochip_get_data(gc); >> + struct mcp_configure *conf; >> + int status; >> + /* after the configure cmd we will need to set the outputs again */ >> + unsigned long mask = ~(mcp->gpio_dir); /* only set outputs */ >> + unsigned long bits = mcp->gpio_val; >> + /* Offsets of alternative pins in config_alt_pins, 0 is not used */ >> + u8 alt_pin_conf[8] = {SSPND, USBCFG, 0, 0, 0, 0, RXLED, TXLED}; >> + u8 config_alt_pins = mcp->config_alt_pins; >> + >> + /* Read in the reset baudrate first, we need it later */ >> + status = mcp_cmd_read_all(mcp); >> + if (status != 0) >> + return status; >> + >> + conf = kzalloc(sizeof(struct mcp_configure), GFP_KERNEL); >> + if (!conf) >> + return -ENOMEM; >> + mutex_lock(&mcp->lock); >> + >> + /* configure will reset the chip! */ >> + conf->cmd = CONFIGURE; >> + conf->io_bmap = (mcp->gpio_dir & ~(1 << gpio_nr)) >> + | (io_direction << gpio_nr); >> + /* Don't overwrite the reset parameters */ >> + conf->baud_h = mcp->baud_h; >> + conf->baud_l = mcp->baud_l; >> + conf->config_alt_options = mcp->config_alt_options; >> + conf->io_default_val_bmap = mcp->gpio_reset_val; >> + /* Adjust alt. func if necessary */ >> + if (alt_pin_conf[gpio_nr]) >> + config_alt_pins &= ~(1 << alt_pin_conf[gpio_nr]); >> + conf->config_alt_pins = config_alt_pins; >> + >> + status = hid_hw_output_report(mcp->hdev, (u8 *) conf, >> + sizeof(struct mcp_set_clear_outputs)); >> + if (status == sizeof(struct mcp_set_clear_outputs)) { >> + mcp->gpio_dir &= ~(1 << gpio_nr); >> + mcp->config_alt_pins = config_alt_pins; >> + } else { >> + return -EIO; >> + } >> + >> + kfree(conf); >> + mutex_unlock(&mcp->lock); > >Mutex unlock could be done before kfree(). > >> + >> + /* Configure CMD will clear all IOs -> rewrite them */ >> + mcp_set_multiple(gc, &mask, &bits); >> + return 0; >> +} >> + >> +static int mcp_direction_input(struct gpio_chip *gc, unsigned int gpio_nr) >> +{ >> + return mcp_set_direction(gc, gpio_nr, MCP2200_DIR_IN); >> +} >> + >> +static int mcp_direction_output(struct gpio_chip *gc, unsigned int gpio_nr, >> + int value) >> +{ >> + int ret; >> + unsigned long mask, bmap_value; >> + >> + mask = (1 << gpio_nr); > >Uneeded () >Does using BIT makes sense here? > >> + bmap_value = (value << gpio_nr); > >Uneeded () > >> + >> + ret = mcp_set_direction(gc, gpio_nr, MCP2200_DIR_OUT); >> + if (ret == 0) >> + mcp_set_multiple(gc, &mask, &bmap_value); >> + return ret; >> +} >> + >> + > >No need for 2 new lines. > >[...] > >> +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; >> + } >> + >> + /* >> + * 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) >> + return ret; >> + >> + mcp->gc = template_chip; >> + mcp->gc.parent = &hdev->dev; >> + >> + ret = gpiochip_add_data(&mcp->gc, mcp); > >devm_gpiochip_add_data() and no .remove function? The gpiochip will be removed in mcp2200_remove > >> + if (ret < 0) { >> + dev_err(&hdev->dev, "Unable to register gpiochip\n"); > >hid_err() to be consistent? > >> + hid_hw_stop(hdev); > >hid_hw_stop() would be called twice. Once here and once because of the >devm_add_action_or_reset() above. I think it is only called once. It will be called when gpiochip_add_data or hid_hw_open returns an error or when the mcp2200_hid_unregister gets called. > > >Just my 2c, > >CJ > >> + return ret; >> + } >> + >> + return 0; >> +} > >[...] > Hi, thanks for your feedback. I have added most of it in my Kernel module. For the view things, I haven't added, I add a comment under your comment. I am sorry for the error in hid-ids.h. It seems I forgot to run a git add hid-ids.h to rename the second USB_DEVICE_ID_MCP2221 into USB_DEVICE_ID_MCP2200. What do you think is the best way to deliver my driver? Should I create a new single patch containg everything I have changed or should I go with the two already created patches, reorder them, fixing the error in hid-ids.h and adding a new patch including the comments from your review? This is my first contribution, that's why I am asking. Best regards, Johannes
