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fel: implement I-Cache hack

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On some new Allwinner SoCs, I-Cache is enabled by BROM but FEL write
command cannot correctly invalidate I-Cache, so thunks will not get
properly executed.

Implement a hack that tries to disable I-Cache each time trying to write
data via FEL, to prevent stall thunks in I-Cache.

Signed-off-by: Icenowy Zheng <uwu@icenowy.me>
This commit is contained in:
Icenowy Zheng 2022-07-06 04:54:15 +08:00
parent 76089c82d0
commit f03565a8eb
2 changed files with 31 additions and 1 deletions
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30
fel_lib.c
View File

@ -40,6 +40,7 @@ struct _felusb_handle {
libusb_device_handle *handle;
int endpoint_out, endpoint_in;
bool iface_detached;
bool icache_hacked;
};
/* a helper function to report libusb errors */
@ -214,7 +215,7 @@ void aw_fel_read(feldev_handle *dev, uint32_t offset, void *buf, size_t len)
}
/* AW_FEL_1_WRITE request */
void aw_fel_write(feldev_handle *dev, const void *buf, uint32_t offset, size_t len)
static void aw_fel_write_raw(feldev_handle *dev, const void *buf, uint32_t offset, size_t len)
{
if (len == 0)
return;
@ -231,6 +232,33 @@ void aw_fel_execute(feldev_handle *dev, uint32_t offset)
aw_read_fel_status(dev);
}
static void aw_disable_icache(feldev_handle *dev)
{
soc_info_t *soc_info = dev->soc_info;
uint32_t arm_code[] = {
/* Clear SCTLR.I */
htole32(0xee110f10), /* mrc 15, 0, r0, cr1, cr0, {0} ;SCTLR */
htole32(0xe3c00a01), /* bic r0, r0, #0x1000 */
htole32(0xee010f10), /* mcr 15, 0, r0, cr1, cr0, {0} ;SCTLR */
/* Invalidate I-Cache */
htole32(0xee070f15), /* mcr 15, 0, r0, cr7, cr5, {0} ;ICIALLU */
/* Barrier to force instruction refetching */
htole32(0xf57ff06f), /* isb sy */
htole32(0xe12fff1e), /* bx lr */
};
aw_fel_write_raw(dev, arm_code, soc_info->scratch_addr, sizeof(arm_code));
aw_fel_execute(dev, soc_info->scratch_addr);
}
void aw_fel_write(feldev_handle *dev, const void *buf, uint32_t offset, size_t len)
{
if (dev->soc_info->icache_fix && !dev->usb->icache_hacked) {
aw_disable_icache(dev);
dev->usb->icache_hacked = true;
}
aw_fel_write_raw(dev, buf, offset, len);
}
/*
* This function is a higher-level wrapper for the FEL write functionality.
* Unlike aw_fel_write() above - which is reserved for internal use - this

2
soc_info.h
View File

@ -113,6 +113,8 @@ typedef struct {
uint32_t rvbar_reg; /* MMIO address of RVBARADDR0_L register */
const watchdog_info *watchdog; /* Used for reset */
bool sid_fix; /* Use SID workaround (read via register) */
/* Use I$ workaround (disable I$ before first write to prevent stale thunk */
bool icache_fix;
/* Use SMC workaround (enter secure mode) if can't read from this address */
uint32_t needs_smc_workaround_if_zero_word_at_addr;
uint32_t sram_size; /* Usable contiguous SRAM at spl_addr */