[U-Boot] [PATCH 08/10] sunxi: Add basic PSCI implementation for A80

Chen-Yu Tsai wens at csie.org
Wed Nov 9 11:21:34 CET 2016


The A80 is a big.LITTLE multi-cluster SoC, with a different layout for
the PRCM and CPUCFG registers. As such it needs a different PSCI
implementation.

This patch adds a basic version that allows bringing up the four cores
in the first cluster. The structure is based on existing sunxi PSCI code.

Signed-off-by: Chen-Yu Tsai <wens at csie.org>
---
 arch/arm/cpu/armv7/sunxi/Makefile    |   4 +
 arch/arm/cpu/armv7/sunxi/psci-mcpm.c | 234 +++++++++++++++++++++++++++++++++++
 2 files changed, 238 insertions(+)
 create mode 100644 arch/arm/cpu/armv7/sunxi/psci-mcpm.c

diff --git a/arch/arm/cpu/armv7/sunxi/Makefile b/arch/arm/cpu/armv7/sunxi/Makefile
index 239c659ec032..b18e5f1fa974 100644
--- a/arch/arm/cpu/armv7/sunxi/Makefile
+++ b/arch/arm/cpu/armv7/sunxi/Makefile
@@ -14,8 +14,12 @@ obj-$(CONFIG_MACH_SUN8I_H3)	+= tzpc.o
 obj-$(CONFIG_MACH_SUN9I)	+= tzpc.o
 
 ifndef CONFIG_SPL_BUILD
+ifdef CONFIG_MACH_SUN9I
+obj-$(CONFIG_ARMV7_PSCI)	+= psci-mcpm.o
+else
 obj-$(CONFIG_ARMV7_PSCI)	+= psci.o
 endif
+endif
 
 ifdef CONFIG_SPL_BUILD
 obj-y	+= fel_utils.o
diff --git a/arch/arm/cpu/armv7/sunxi/psci-mcpm.c b/arch/arm/cpu/armv7/sunxi/psci-mcpm.c
new file mode 100644
index 000000000000..3ede07cace2c
--- /dev/null
+++ b/arch/arm/cpu/armv7/sunxi/psci-mcpm.c
@@ -0,0 +1,234 @@
+/*
+ * Copyright (C) 2016
+ * Author: Chen-Yu Tsai <wens at csie.org>
+ *
+ * Based on assembly code by Marc Zyngier <marc.zyngier at arm.com>,
+ * which was based on code by Carl van Schaik <carl at ok-labs.com>.
+ *
+ * SPDX-License-Identifier:	GPL-2.0
+ */
+#include <config.h>
+#include <common.h>
+
+#include <asm/arch/cpu.h>
+#include <asm/arch/cpucfg_sun9i.h>
+#include <asm/arch/prcm_sun9i.h>
+#include <asm/armv7.h>
+#include <asm/io.h>
+#include <asm/psci.h>
+#include <asm/secure.h>
+
+#include <linux/bitops.h>
+
+/*
+ * NOTE dense CPU IDs (0~3 for first cluster of 4 cores, 4~7 for the
+ * second cluster) are used throughout the PSCI code. Any MPIDR style
+ * values must be converted.
+ */
+
+/*
+ * Provide a dense CPU ID for 2-cluster systems. This must be coded in
+ * assembly as it gets called from psci_stack_setup, when the stack isn't
+ * available yet.
+ *
+ * Only r0 and r3 is usable. r8 - r12 are available if this function is
+ * only called from psci_stack_setup, which we cannot guarantee.
+ */
+u32 __secure __naked psci_get_cpu_id(void)
+{
+	asm volatile (
+		"mrc	p15, 0, r3, c0, c0, 5	@ Get MPIDR\n"
+		"lsr	r0, r3, #6\n"
+		"and	r3, r3, #3\n"
+		"and	r0, r0, #4\n"
+		"orr	r0, r0, r3\n"
+		"bx	lr\n"
+	);
+
+	/*
+	 * The last five lines are the compiler generated assembly code for
+	 *
+	 *	return (reg & 0x3) | (((reg >> 8) & 0x1) << 2);
+	 *
+	 * We can't guarantee that all compilers correctly use only r0 and
+	 * r3, so we use inline assembly here.
+	 */
+}
+
+static void __secure cp15_write_cntp_tval(u32 tval)
+{
+	asm volatile ("mcr p15, 0, %0, c14, c2, 0" : : "r" (tval));
+}
+
+static void __secure cp15_write_cntp_ctl(u32 val)
+{
+	asm volatile ("mcr p15, 0, %0, c14, c2, 1" : : "r" (val));
+}
+
+static u32 __secure cp15_read_cntp_ctl(void)
+{
+	u32 val;
+
+	asm volatile ("mrc p15, 0, %0, c14, c2, 1" : "=r" (val));
+
+	return val;
+}
+
+#define ONE_US (CONFIG_TIMER_CLK_FREQ / 1000000)
+
+/* Use a different name to avoid clashing with the non-secure function */
+static void __secure __udelay_sec(unsigned long us)
+{
+	u32 reg = ONE_US * us;
+
+	cp15_write_cntp_tval(reg);
+	isb();
+	cp15_write_cntp_ctl(3);
+
+	do {
+		isb();
+		reg = cp15_read_cntp_ctl();
+	} while (!(reg & BIT(2)));
+
+	cp15_write_cntp_ctl(0);
+	isb();
+}
+
+static void __secure clamp_release(u32 *clamp)
+{
+	writel(0xff, clamp);
+	__udelay_sec(10);
+	writel(0xfe, clamp);
+	__udelay_sec(10);
+	writel(0xf8, clamp);
+	__udelay_sec(10);
+	writel(0xf0, clamp);
+	__udelay_sec(10);
+	writel(0x00, clamp);
+}
+
+static void __secure clamp_set(u32 *clamp)
+{
+	writel(0xff, clamp);
+}
+
+static void __secure sunxi_core_power_switch(u32 *clamp, u32 *pwroff,
+					     bool on, int cpu)
+{
+	if (on) {
+		/* Release power clamp */
+		clamp_release(clamp);
+
+		__udelay_sec(20);
+
+		/* Clear power gating */
+		clrbits_le32(pwroff, BIT(cpu));
+	} else {
+		/* Set power gating */
+		setbits_le32(pwroff, BIT(cpu));
+
+		__udelay_sec(20);
+
+		/* Activate power clamp */
+		clamp_set(clamp);
+	}
+}
+
+static void __secure sunxi_cpu_set_power(int cpu, bool on)
+{
+	struct sunxi_prcm_reg *prcm =
+		(struct sunxi_prcm_reg *)SUNXI_PRCM_BASE;
+	int cluster = (cpu >> 2) & 0x1;
+	int core = cpu & 0x3;
+
+	sunxi_core_power_switch(&prcm->cpu_pwr_clamp[cluster][core],
+				&prcm->cpu_pwroff[cluster], on, core);
+}
+
+static u32 __secure cp15_read_scr(void)
+{
+	u32 scr;
+
+	asm volatile ("mrc p15, 0, %0, c1, c1, 0" : "=r" (scr));
+
+	return scr;
+}
+
+static void __secure cp15_write_scr(u32 scr)
+{
+	asm volatile ("mcr p15, 0, %0, c1, c1, 0" : : "r" (scr));
+	isb();
+}
+
+int __secure psci_cpu_on(u32 __always_unused unused, u32 mpidr, u32 pc)
+{
+	struct sunxi_cpucfg_reg *cpucfg =
+		(struct sunxi_cpucfg_reg *)SUNXI_CPUCFG_BASE;
+	struct sunxi_prcm_reg *prcm =
+		(struct sunxi_prcm_reg *)SUNXI_PRCM_BASE;
+	u32 cluster = (mpidr >> 8) & 0x1;
+	u32 cpu = mpidr & 0x3;
+	u32 cpuid = cpu | (cluster << 2);
+
+	/* TODO We don't support multi-cluster yet */
+	if (cluster > 0)
+		return ARM_PSCI_RET_INVAL;
+
+	/* store target PC */
+	psci_save_target_pc(cpuid, pc);
+
+	/* Set secondary core power on PC */
+	writel((u32)&psci_cpu_entry, &prcm->cpu_soft_entry);
+
+	/* Assert power-on reset on target CPU */
+	clrbits_le32(&prcm->cpu_rst[cluster], BIT(cpu));
+
+	/* Cortex-A7: hold L1 cache reset disable signal low */
+	if (cluster == 0)
+		clrbits_le32(&cpucfg->cluster[cluster].ctrl0,
+			     CPUCFG_CX_CTRL0_L1_RST_DISABLE(cpu));
+
+	/* Lock CPU (Disable external debug access) */
+	clrbits_le32(&cpucfg->cluster_reset[cluster],
+		     CPUCFG_CX_RST_DBG(cpu));
+
+	/* Cortex-A7: Assert ETM reset */
+	if (cluster == 0)
+		clrbits_le32(&cpucfg->cluster_reset[cluster],
+			     CPUCFG_CX_RST_ETM(cpu));
+
+	/*
+	 * Allwinner code also asserts resets for NEON on A15. According
+	 * to ARM manuals, asserting power-on reset is sufficient.
+	 */
+
+	/* Power up target CPU */
+	sunxi_cpu_set_power(cpu, true);
+
+	/* De-assert power-on reset on target CPU */
+	setbits_le32(&prcm->cpu_rst[cluster], BIT(cpu));
+
+	/* De-assert core reset on target CPU */
+	setbits_le32(&cpucfg->cluster_reset[cluster],
+		     CPUCFG_CX_RST_CORE(cpu));
+
+	/* Cortex-A7: De-assert ETM reset */
+	if (cluster == 0)
+		setbits_le32(&cpucfg->cluster_reset[cluster],
+			     CPUCFG_CX_RST_ETM(cpu));
+
+	/* Unlock CPU (Disable external debug access) */
+	setbits_le32(&cpucfg->cluster_reset[cluster],
+		     CPUCFG_CX_RST_DBG(cpu));
+
+	return ARM_PSCI_RET_SUCCESS;
+}
+
+void __secure psci_arch_init(void)
+{
+	u32 reg;
+
+	reg = cp15_read_scr();
+	reg &= ~BIT(0); /* Secure mode */
+	cp15_write_scr(reg);
+}
-- 
2.10.2



More information about the U-Boot mailing list