feat(msm8916): allow booting secondary CPU cores

Add support for the PSCI CPU_ON call to allow booting secondary CPU
cores. On cold boot they need to be booted with a special register
sequence. Also, the "boot remapper" needs to be configured to point to
the BL31_BASE, so the CPUs actually start executing BL31 after reset.

Change-Id: I406c508070ccb046bfdefd51554f12e1db671fd4
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
diff --git a/plat/qti/msm8916/msm8916_cpu_boot.c b/plat/qti/msm8916/msm8916_cpu_boot.c
new file mode 100644
index 0000000..b3f51f6
--- /dev/null
+++ b/plat/qti/msm8916/msm8916_cpu_boot.c
@@ -0,0 +1,66 @@
+/*
+ * Copyright (c) 2021, Stephan Gerhold <stephan@gerhold.net>
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch_helpers.h>
+#include <drivers/delay_timer.h>
+#include <lib/mmio.h>
+
+#include <msm8916_mmap.h>
+#include "msm8916_pm.h"
+
+#define CPU_PWR_CTL			0x4
+#define APC_PWR_GATE_CTL		0x14
+
+#define CPU_PWR_CTL_CLAMP		BIT_32(0)
+#define CPU_PWR_CTL_CORE_MEM_CLAMP	BIT_32(1)
+#define CPU_PWR_CTL_L1_RST_DIS		BIT_32(2)
+#define CPU_PWR_CTL_CORE_MEM_HS		BIT_32(3)
+#define CPU_PWR_CTL_CORE_RST		BIT_32(4)
+#define CPU_PWR_CTL_COREPOR_RST		BIT_32(5)
+#define CPU_PWR_CTL_GATE_CLK		BIT_32(6)
+#define CPU_PWR_CTL_CORE_PWRD_UP	BIT_32(7)
+
+#define APC_PWR_GATE_CTL_GHDS_EN	BIT_32(0)
+#define APC_PWR_GATE_CTL_GHDS_CNT(cnt)	((cnt) << 24)
+
+/* Boot a secondary CPU core for the first time. */
+void msm8916_cpu_boot(unsigned int core)
+{
+	uintptr_t acs = APCS_ALIAS_ACS(core);
+	uint32_t pwr_ctl;
+
+	pwr_ctl = CPU_PWR_CTL_CLAMP | CPU_PWR_CTL_CORE_MEM_CLAMP |
+		  CPU_PWR_CTL_CORE_RST | CPU_PWR_CTL_COREPOR_RST;
+	mmio_write_32(acs + CPU_PWR_CTL, pwr_ctl);
+	dsb();
+
+	mmio_write_32(acs + APC_PWR_GATE_CTL, APC_PWR_GATE_CTL_GHDS_EN |
+		      APC_PWR_GATE_CTL_GHDS_CNT(16));
+	dsb();
+	udelay(2);
+
+	pwr_ctl &= ~CPU_PWR_CTL_CORE_MEM_CLAMP;
+	mmio_write_32(acs + CPU_PWR_CTL, pwr_ctl);
+	dsb();
+
+	pwr_ctl |= CPU_PWR_CTL_CORE_MEM_HS;
+	mmio_write_32(acs + CPU_PWR_CTL, pwr_ctl);
+	dsb();
+	udelay(2);
+
+	pwr_ctl &= ~CPU_PWR_CTL_CLAMP;
+	mmio_write_32(acs + CPU_PWR_CTL, pwr_ctl);
+	dsb();
+	udelay(2);
+
+	pwr_ctl &= ~(CPU_PWR_CTL_CORE_RST | CPU_PWR_CTL_COREPOR_RST);
+	mmio_write_32(acs + CPU_PWR_CTL, pwr_ctl);
+	dsb();
+
+	pwr_ctl |= CPU_PWR_CTL_CORE_PWRD_UP;
+	mmio_write_32(acs + CPU_PWR_CTL, pwr_ctl);
+	dsb();
+}