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Restore GPIO15 state after modifying it for USB enumeration fix (#80)

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Restore GPIO15 state after usb enumeration fix
Co-authored-by: Luke Wren <wren6991@gmail.com>
This commit is contained in:
Liam Fraser 2021-02-05 15:22:23 +00:00 committed by graham sanderson
parent c44d5026db
commit 5514401bf4
1 changed files with 31 additions and 7 deletions
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38
src/rp2_common/pico_fix/rp2040_usb_device_enumeration/rp2040_usb_device_enumeration.c
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@ -8,6 +8,8 @@
#include "pico/time.h"
#include "hardware/structs/usb.h"
#include "hardware/gpio.h"
#include "hardware/structs/iobank0.h"
#include "hardware/structs/padsbank0.h"
#include "pico/fix/rp2040_usb_device_enumeration.h"
#define LS_SE0 0b00
@ -74,20 +76,37 @@ int64_t hw_enumeration_fix_force_ls_j_done(alarm_id_t id, void *user_data) {
return 0;
}
static uint32_t gpio_ctrl_prev = 0;
static uint32_t pad_ctrl_prev = 0;
static const uint dp = 15;
static const uint dm = 16;
static void hw_enumeration_fix_force_ls_j(void) {
// Force LS_J
const uint dp = 15;
//const uint dm = 16;
gpio_set_function(dp, 8);
// TODO: assert dm is not funcseld to usb
// DM must be 0 for this to work. This is true if it is selected
// to any other function. fn 8 on this pin is only for debug so shouldn't
// be selected
if (gpio_get_function(dm) == 8) {
panic("Not expecting DM to be function 8");
}
// Before changing any pin state, take a copy of the current gpio control register
gpio_ctrl_prev = iobank0_hw->io[dp].ctrl;
// Also take a copy of the pads register
pad_ctrl_prev = padsbank0_hw->io[dp];
// Enable bus keep and force pin to tristate, so USB DP muxing doesn't affect
// pin state
gpio_set_pulls(dp, true, true);
gpio_set_oeover(dp, GPIO_OVERRIDE_LOW);
// Select function 8 (USB debug muxing) without disturbing other controls
hw_write_masked(&iobank0_hw->io[dp].ctrl,
8 << IO_BANK0_GPIO15_CTRL_FUNCSEL_LSB, IO_BANK0_GPIO15_CTRL_FUNCSEL_BITS);
// J state is a differential 1 for a full speed device so
// DP = 1 and DM = 0. Don't actually need to set DM low as it
// is already gated assuming it isn't funcseld.
gpio_set_inover(dp, GPIO_OVERRIDE_HIGH);
// TODO: What to do about existing DP state here?
// Force PHY pull up to stay before switching away from the phy
hw_set_alias(usb_hw)->phy_direct = USB_USBPHY_DIRECT_DP_PULLUP_EN_BITS;
hw_set_alias(usb_hw)->phy_direct_override = USB_USBPHY_DIRECT_OVERRIDE_DP_PULLUP_EN_OVERRIDE_EN_BITS;
@ -118,4 +137,9 @@ static void hw_enumeration_fix_finish(void) {
// Get rid of DP pullup override
hw_clear_alias(usb_hw)->phy_direct_override = USB_USBPHY_DIRECT_OVERRIDE_DP_PULLUP_EN_OVERRIDE_EN_BITS;
// Finally, restore the gpio ctrl value back to GPIO15
iobank0_hw->io[dp].ctrl = gpio_ctrl_prev;
// Restore the pad ctrl value
padsbank0_hw->io[dp] = pad_ctrl_prev;
}