firmware for my Touchscreen E-Paper Input Module for Framework Laptop 16
eepy: remove broken InvalidateCache syscall This syscall caused weird HardFaults, and also invalidated the entire XIP cache which isn't ideal. The flash syscalls now automatically flush the cache for only the area that was modified, by writing to the flash memory-mapped addresses as specified in the RP2040 datasheet section 2.6.3.2.
+25
-28
+1
-7
eepy-launcher/src/serial.rs
+1
-7
eepy-launcher/src/serial.rs
···
4
4
use usb_device::device::UsbDevice;
5
5
use usbd_serial::SerialPort;
6
6
use eepy_serial::{Response, SerialCommand};
7
-
use eepy_sys::flash::{erase_and_program, invalidate_cache};
7
+
use eepy_sys::flash::erase_and_program;
8
8
use eepy_sys::image::{refresh, write_image, RefreshBlockMode};
9
9
use eepy_sys::IMAGE_BYTES;
10
10
use eepy_sys::input::{next_event, set_touch_enabled};
···
197
197
if *page == num_pages {
198
198
debug("finalising");
199
199
unsafe { write_flash(&buf[0..4096], 1, 0) };
200
-
201
-
debug("invalidating XIP cache");
202
-
// Invalidate the XIP cache, in case something from the flash area
203
-
// we just wrote is in there
204
-
unsafe { invalidate_cache() };
205
-
debug("invalidated XIP cache");
206
200
207
201
NEEDS_REFRESH_PROGRAMS.store(true, Ordering::Relaxed);
208
202
info("Finished writing program");
-8
eepy-sys/src/flash.rs
-8
eepy-sys/src/flash.rs
···
8
8
Erase = 0,
9
9
Program = 1,
10
10
EraseAndProgram = 2,
11
-
InvalidateCache = 3,
12
11
}
13
12
14
13
pub unsafe fn erase(start_addr: u32, len: u32) {
···
37
36
in start_addr,
38
37
in data.len(),
39
38
in data.as_ptr(),
40
-
);
41
-
}
42
-
43
-
pub unsafe fn invalidate_cache() {
44
-
syscall!(
45
-
SyscallNumber::Flash,
46
-
in FlashSyscall::InvalidateCache,
47
39
);
48
40
}
+4
-1
eepy/src/main.rs
+4
-1
eepy/src/main.rs
···
132
132
// Region 3: Flash - start: 0x10000000, length 16M
133
133
core.MPU.rnr.write(3);
134
134
core.MPU.rbar.write(0x10000000);
135
+
// NOTE: we of course can't actually write to the flash via the XIP memory map, but
136
+
// performing writes to the flash memory region flushes the XIP cache for that area of
137
+
// flash, so the kernel still needs write access
135
138
core.MPU.rasr.write(
136
139
(0b0 << 28) // disable XN
137
-
| (0b110 << 24) // AP: privileged or unprivileged read-only
140
+
| (0b010 << 24) // AP: privileged RW, unprivileged RO
138
141
| (0b000 << 19) // TEX
139
142
| (0b110 << 16) // S, C, B: shared, write-through
140
143
| (0b00000000 << 8) // all subregions enabled
+20
-12
eepy/src/syscall.rs
+20
-12
eepy/src/syscall.rs
···
248
248
}
249
249
250
250
mod flash {
251
-
use core::arch::asm;
252
251
use core::sync::atomic::Ordering;
253
252
use eepy_sys::flash::FlashSyscall;
254
253
use eepy_sys::header::{SLOT_SIZE, XIP_BASE};
255
-
use fw16_epd_bsp::pac;
256
254
use crate::exception::StackFrame;
257
255
use crate::{FLASHING, FLASHING_ACK};
258
256
···
261
259
Some(FlashSyscall::Erase) => handle_erase(stack_values),
262
260
Some(FlashSyscall::Program) => handle_program(stack_values),
263
261
Some(FlashSyscall::EraseAndProgram) => handle_erase_and_program(stack_values),
264
-
Some(FlashSyscall::InvalidateCache) => handle_invalidate_cache(),
265
262
None => panic!("illegal syscall"),
266
263
}
267
264
}
···
304
301
cortex_m::asm::sev();
305
302
}
306
303
304
+
fn flush_cache_range(start_addr: u32, len: u32) {
305
+
// RP2040 Datasheet 2.6.3.2:
306
+
// "A write to the 0x10… mirror will look up the addressed location in the cache, and delete
307
+
// any matching entry found. Writing to all word-aligned locations in an address range (e.g.
308
+
// a flash sector that has just been erased and reprogrammed) therefore eliminates the
309
+
// possibility of stale cached data in this range, without suffering the effects of a
310
+
// complete cache flush."
311
+
312
+
unsafe {
313
+
let start_ptr: *mut u32 = XIP_BASE.add(start_addr as usize).cast_mut().cast();
314
+
let words = len / 4;
315
+
for _ in 0..words {
316
+
start_ptr.add(words as usize).write_volatile(0);
317
+
}
318
+
}
319
+
}
320
+
307
321
fn handle_erase(stack_values: &mut StackFrame) {
308
322
let start_addr = stack_values.r1 as u32;
309
323
let len = stack_values.r2 as u32;
···
315
329
begin();
316
330
unsafe {
317
331
rp2040_flash::flash::flash_range_erase(start_addr, len, true);
332
+
flush_cache_range(start_addr, len);
318
333
}
319
334
end();
320
335
}
···
330
345
begin();
331
346
unsafe {
332
347
rp2040_flash::flash::flash_range_program(start_addr, data, true);
348
+
flush_cache_range(start_addr, data.len() as u32);
333
349
}
334
350
end();
335
351
}
···
345
361
begin();
346
362
unsafe {
347
363
rp2040_flash::flash::flash_range_erase_and_program(start_addr, data, true);
364
+
flush_cache_range(start_addr, data.len() as u32);
348
365
}
349
366
end();
350
-
}
351
-
352
-
fn handle_invalidate_cache() {
353
-
unsafe {
354
-
let xip = pac::Peripherals::steal().XIP_CTRL;
355
-
xip.flush().write(|w| w.flush().set_bit());
356
-
xip.flush().read();
357
-
asm!("dsb", "isb");
358
-
};
359
367
}
360
368
}