[U-Boot] [PATCH v2 3/5] rockchip: back-to-bootrom: rk3188: chain from SPL via TPL to the BROM

Philipp Tomsich
2017-09-18T18:18:26Z

The RK3188 implementation previously passed the address of the stack
frame created during save_boot_params via pmu->os_reg[2]. This was not
strictly necessary, as the save_boot_params() function was called
twice (first: for TPL, saving the context for the BROM; next: for SPL,
saving the context for the TPL) and a back-to-bootrom from the SPL
would thus return to TPL.

To simplify things, we now assume that the state of the TPL is not
corrupted during SPL (the binaries are non-overlapping) and that the
SPL can safely return to TPL using the back-to-bootrom mechanism.
Consequently, the TPL should expect the SPL to return control and then
further return to the actual bootrom by performing another
back-to-bootrom transition.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
---

Changes in v2:
- [added in v2] chain back_to_bootrom calls for SPL, first returning
to the TPL (using the same mechanism) and the to the BROM from the
TPL

arch/arm/mach-rockchip/rk3188-board-spl.c | 10 ----------
arch/arm/mach-rockchip/rk3188-board-tpl.c | 17 ++++++++++-------
2 files changed, 10 insertions(+), 17 deletions(-)

diff --git a/arch/arm/mach-rockchip/rk3188-board-spl.c b/arch/arm/mach-rockchip/rk3188-board-spl.c
index d3866bf..05d4ae6 100644
--- a/arch/arm/mach-rockchip/rk3188-board-spl.c
+++ b/arch/arm/mach-rockchip/rk3188-board-spl.c
@@ -101,7 +101,6 @@ static int setup_arm_clock(void)
void board_init_f(ulong dummy)
{
struct udevice *pinctrl, *dev;
- struct rk3188_pmu *pmu;
int ret;

/* Example code showing how to enable the debug UART on RK3188 */
@@ -145,15 +144,6 @@ void board_init_f(ulong dummy)
return;
}

- /*
- * Recover the bootrom's stackpointer.
- * For whatever reason needs to run after rockchip_get_clk.
- */
- pmu = syscon_get_first_range(ROCKCHIP_SYSCON_PMU);
- if (IS_ERR(pmu))
- error("pmu syscon returned %ld\n", PTR_ERR(pmu));
- SAVE_SP_ADDR = readl(&pmu->sys_reg[2]);
-
ret = uclass_get_device(UCLASS_PINCTRL, 0, &pinctrl);
if (ret) {
debug("Pinctrl init failed: %d\n", ret);
diff --git a/arch/arm/mach-rockchip/rk3188-board-tpl.c b/arch/arm/mach-rockchip/rk3188-board-tpl.c
index b458ef6..c714278 100644
--- a/arch/arm/mach-rockchip/rk3188-board-tpl.c
+++ b/arch/arm/mach-rockchip/rk3188-board-tpl.c
@@ -21,15 +21,16 @@ static int rk3188_num_entries __attribute__ ((section(".data")));

static void jump_to_spl(void)
{
- typedef void __noreturn (*image_entry_noargs_t)(void);
+ typedef void (*image_entry_noargs_t)(void);

- struct rk3188_pmu * const pmu = (void *)PMU_BASE;
image_entry_noargs_t tpl_entry =
(image_entry_noargs_t)(unsigned long)SPL_ENTRY;

- /* Store the SAVE_SP_ADDR in a location shared with SPL. */
- writel(SAVE_SP_ADDR, &pmu->sys_reg[2]);
tpl_entry();
+ /*
+ * If the SPL stage triggers a 'return to bootrom', it will
+ * return to here.
+ */
}

void board_init_f(ulong dummy)
@@ -77,10 +78,12 @@ void board_init_f(ulong dummy)
back_to_bootrom();
} else {
/*
- * TPL part of the loader should now wait for us
- * at offset 0xC00 in the sram. Should never return
- * from there.
+ * SPL part of the loader should now wait for us at
+ * offset 0xC00 in the sram. If the SPL returns to us,
+ * we should in turn return to the BROM (i.e. chain
+ * through).
*/
jump_to_spl();
+ back_to_bootrom();
}
}
--
2.1.4