xilinx: versal: add firmware access to PMC multi Boot mode register

Added extended support for retrieving the PMC muti boot mode
register via the firmware interface, which is preferred when
U-Boot runs in EL2 and cannot directly access PMC registers
via raw reads. Ideally, all secure registers should be accessed
via xilinx_pm_request(). Introduced the secure
zynqmp_pm_get_pmc_multi_boot_reg() call, which uses
xilinx_pm_request() to read the PMC multi boot mode register.

BootROM increments the MultiBoot register (PMC_MULTI_BOOT) read
address offset by 32 KB and retries. For SD and eMMC boot modes,
it can search up to 8191 FAT files for the identification string.
A 13-bit mask (0x1FFF) is applied to PMC_MULTI_BOOT_MASK to obtain
the correct values in BootROM.

Signed-off-by: Prasad Kummari <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Michal Simek <[email protected]>

1 files changed, 23 insertions, 0 deletions

diff --git a/drivers/firmware/firmware-zynqmp.c b/drivers/firmware/firmware-zynqmp.c
index 2adc132b4cc..584397ba29a 100644
--- a/drivers/firmware/firmware-zynqmp.c
+++ b/drivers/firmware/firmware-zynqmp.c
@@ -218,6 +218,29 @@ u32 zynqmp_pm_get_bootmode_reg(void)
 	return ret_payload[1];
 }
 
+u32 zynqmp_pm_get_pmc_multi_boot_reg(void)
+{
+	int ret;
+	u32 ret_payload[PAYLOAD_ARG_CNT];
+
+	ret = zynqmp_pm_is_function_supported(PM_IOCTL, IOCTL_READ_REG);
+	if (ret) {
+		printf("%s: IOCTL_READ_REG is not supported failed with error code: %d\n"
+		       , __func__, ret);
+		return 0;
+	}
+
+	ret = xilinx_pm_request(PM_IOCTL, PM_REG_PMC_GLOBAL_NODE, IOCTL_READ_REG,
+				PMC_MULTI_BOOT_MODE_REG_OFFSET, 0, ret_payload);
+	if (ret) {
+		printf("%s: node 0x%x: get_bootmode 0x%x failed\n",
+		       __func__, PM_REG_PMC_GLOBAL_NODE, PMC_MULTI_BOOT_MODE_REG_OFFSET);
+		return 0;
+	}
+
+	return ret_payload[1];
+}
+
 int zynqmp_pm_feature(const u32 api_id)
 {
 	int ret;