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ARM: EXYNOS: Map SYSRAM through generic SRAM bindings

PATCH Superseded Sachin Kamat 3 participants 5 messages May 2, 2014 – May 4, 2014

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PATCH v2 1/2 ARM: EXYNOS: Map SYSRAM through generic SRAM bindings

Instead of hardcoding the SYSRAM details for each SoC, pass this information through device tree (DT) and make the code SoC agnostic. Generic SRAM bindings are used for achieving this.

---
This patch is based on linux next (next-20140501) on top of my Kconfig consolidation patch
http://comments.gmane.org/gmane.linux.kernel.samsung-soc/28642

Changes since v1:
Type and presence of sram nodes is SoC/board dependent. V1 mandated the presence of both the nodes and used to return an error if one of the nodes was absent and thus fail the boot altogether. Removed this dependency.

Tested on 4210/4412 Origen, 5250/5420 Arndale and SMDK5420 boards.

---
 arch/arm/Kconfig                                |    1 +
 arch/arm/boot/dts/exynos4210-universal_c210.dts |   17 ++++++
 arch/arm/boot/dts/exynos4210.dtsi               |   18 +++++++
 arch/arm/boot/dts/exynos4x12.dtsi               |   18 +++++++
 arch/arm/boot/dts/exynos5250.dtsi               |   18 +++++++
 arch/arm/boot/dts/exynos5420.dtsi               |   18 +++++++
 arch/arm/mach-exynos/common.h                   |    1 +
 arch/arm/mach-exynos/exynos.c                   |   64 -----------------------
 arch/arm/mach-exynos/firmware.c                 |    8 ++-
 arch/arm/mach-exynos/include/mach/map.h         |    7 ---
 arch/arm/mach-exynos/platsmp.c                  |   33 ++++++++++--
 11 files changed, 128 insertions(+), 75 deletions(-)
arch/arm/Kconfig +1 -0
index a6aaaad19b1a..f66ea9453df9 100644
@@ -855,6 +855,7 @@ config ARCH_EXYNOS
 	select S5P_DEV_MFC
 	select SAMSUNG_DMADEV
 	select SPARSE_IRQ
+	select SRAM
 	select USE_OF
 	help
 	  Support for SAMSUNG's EXYNOS SoCs (EXYNOS4/5)
arch/arm/boot/dts/exynos4210-universal_c210.dts +17 -0
index 63e34b24b04f..8d4de5c0d0c7 100644
@@ -28,6 +28,23 @@
 		bootargs = "console=ttySAC2,115200N8 root=/dev/mmcblk0p5 rw rootwait earlyprintk panic=5 maxcpus=1";
 	};
 
+	sram at 02020000 {
+		status = "disabled";
+	};
+
+	sram at 02025000 {
+		compatible = "mmio-sram";
+		reg = <0x02025000 0x1000>;
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges = <0 0x02025000 0x1000>;
+
+		smp-sram at 0 {
+			compatible = "samsung,exynos4210-sram";
+			reg = <0x0 0x1000>;
+		};
+	};
+
 	mct at 10050000 {
 		compatible = "none";
 	};
arch/arm/boot/dts/exynos4210.dtsi +18 -0
index cacf6140dd2f..d3d727b0c263 100644
@@ -31,6 +31,24 @@
 		pinctrl2 = &pinctrl_2;
 	};
 
+	sram at 02020000 {
+		compatible = "mmio-sram";
+		reg = <0x02020000 0x20000>;
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges = <0 0x02020000 0x20000>;
+
+		smp-sram at 0 {
+			compatible = "samsung,exynos4210-sram";
+			reg = <0x0 0x1000>;
+		};
+
+		smp-sram at 1f000 {
+			compatible = "samsung,exynos4210-sram-ns";
+			reg = <0x1f000 0x1000>;
+		};
+	};
+
 	pd_lcd1: lcd1-power-domain at 10023CA0 {
 		compatible = "samsung,exynos4210-pd";
 		reg = <0x10023CA0 0x20>;
arch/arm/boot/dts/exynos4x12.dtsi +18 -0
index c4a9306f8529..75fb3e7e3999 100644
@@ -37,6 +37,24 @@
 		interrupts = <2 2>, <3 2>, <18 2>, <19 2>;
 	};
 
+	sram at 02020000 {
+		compatible = "mmio-sram";
+		reg = <0x02020000 0x40000>;
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges = <0 0x02020000 0x40000>;
+
+		smp-sram at 0 {
+			compatible = "samsung,exynos4210-sram";
+			reg = <0x0 0x1000>;
+		};
+
+		smp-sram at 2f000 {
+			compatible = "samsung,exynos4210-sram-ns";
+			reg = <0x2f000 0x1000>;
+		};
+	};
+
 	pd_isp: isp-power-domain at 10023CA0 {
 		compatible = "samsung,exynos4210-pd";
 		reg = <0x10023CA0 0x20>;
arch/arm/boot/dts/exynos5250.dtsi +18 -0
index 37423314a028..8d724d56a5c6 100644
@@ -72,6 +72,24 @@
 		};
 	};
 
+	sram at 02020000 {
+		compatible = "mmio-sram";
+		reg = <0x02020000 0x30000>;
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges = <0 0x02020000 0x30000>;
+
+		smp-sram at 0 {
+			compatible = "samsung,exynos4210-sram";
+			reg = <0x0 0x1000>;
+		};
+
+		smp-sram at 2f000 {
+			compatible = "samsung,exynos4210-sram-ns";
+			reg = <0x2f000 0x1000>;
+		};
+	};
+
 	pd_gsc: gsc-power-domain at 10044000 {
 		compatible = "samsung,exynos4210-pd";
 		reg = <0x10044000 0x20>;
arch/arm/boot/dts/exynos5420.dtsi +18 -0
index c3a9a66c5767..ff496adfabde 100644
@@ -110,6 +110,24 @@
 		};
 	};
 
+	sram at 02020000 {
+		compatible = "mmio-sram";
+		reg = <0x02020000 0x54000>;
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges = <0 0x02020000 0x54000>;
+
+		smp-sram at 0 {
+			compatible = "samsung,exynos4210-sram";
+			reg = <0x0 0x1000>;
+		};
+
+		smp-sram at 53000 {
+			compatible = "samsung,exynos4210-sram-ns";
+			reg = <0x53000 0x1000>;
+		};
+	};
+
 	clock: clock-controller at 10010000 {
 		compatible = "samsung,exynos5420-clock";
 		reg = <0x10010000 0x30000>;
arch/arm/mach-exynos/common.h +1 -0
index 9ef3f83efaff..47cbab0f008e 100644
@@ -18,6 +18,7 @@
 void mct_init(void __iomem *base, int irq_g0, int irq_l0, int irq_l1);
 
 struct map_desc;
+extern void __iomem *sram_ns_base_addr;
 void exynos_init_io(void);
 void exynos_restart(enum reboot_mode mode, const char *cmd);
 void exynos_cpuidle_init(void);
arch/arm/mach-exynos/exynos.c +0 -64

82 lines not on this page · raw message

arch/arm/mach-exynos/firmware.c +7 -1
index 932129ef26c6..7d583cb73850 100644
@@ -18,6 +18,7 @@
 
 #include <mach/map.h>
 
+#include "common.h"
 #include "smc.h"
 
 static int exynos_do_idle(void)
@@ -34,7 +35,12 @@ static int exynos_cpu_boot(int cpu)
 
 static int exynos_set_cpu_boot_addr(int cpu, unsigned long boot_addr)
 {
-	void __iomem *boot_reg = S5P_VA_SYSRAM_NS + 0x1c + 4*cpu;
+	void __iomem *boot_reg;
+
+	if (!sram_ns_base_addr)
+		return 0;
+
+	boot_reg = sram_ns_base_addr + 0x1c + 4*cpu;
 
 	__raw_writel(boot_addr, boot_reg);
 	return 0;
arch/arm/mach-exynos/include/mach/map.h +0 -7
index 7b046b59d9ec..548269a60634 100644
@@ -23,13 +23,6 @@
 
 #include <plat/map-s5p.h>
 
-#define EXYNOS4_PA_SYSRAM0		0x02025000
-#define EXYNOS4_PA_SYSRAM1		0x02020000
-#define EXYNOS5_PA_SYSRAM		0x02020000
-#define EXYNOS4210_PA_SYSRAM_NS		0x0203F000
-#define EXYNOS4x12_PA_SYSRAM_NS		0x0204F000
-#define EXYNOS5250_PA_SYSRAM_NS		0x0204F000
-
 #define EXYNOS_PA_CHIPID		0x10000000
 
 #define EXYNOS4_PA_SYSCON		0x10010000
arch/arm/mach-exynos/platsmp.c +30 -3
index 03e5e9f94705..0aac03204f9f 100644
@@ -20,6 +20,7 @@
 #include <linux/jiffies.h>
 #include <linux/smp.h>
 #include <linux/io.h>
+#include <linux/of_address.h>
 
 #include <asm/cacheflush.h>
 #include <asm/smp_plat.h>
@@ -33,11 +34,33 @@
 
 extern void exynos4_secondary_startup(void);
 
+static void __iomem *sram_base_addr;
+void __iomem *sram_ns_base_addr;
+
+static void __init exynos_smp_prepare_sram(void)
+{
+	struct device_node *node;
+
+	node = of_find_compatible_node(NULL, NULL, "samsung,exynos4210-sram");
+	if (node) {
+		sram_base_addr = of_iomap(node, 0);
+		if (!sram_base_addr)
+			pr_err("Secondary CPU boot address not found\n");
+	}
+
+	node = of_find_compatible_node(NULL, NULL, "samsung,exynos4210-sram-ns");
+	if (node) {
+		sram_ns_base_addr = of_iomap(node, 0);
+		if (!sram_ns_base_addr)
+			pr_err("Secondary CPU boot address not found\n");
+	}
+}
+
 static inline void __iomem *cpu_boot_reg_base(void)
 {
 	if (soc_is_exynos4210() && samsung_rev() == EXYNOS4210_REV_1_1)
 		return S5P_INFORM5;
-	return S5P_VA_SYSRAM;
+	return sram_base_addr;
 }
 
 static inline void __iomem *cpu_boot_reg(int cpu)
@@ -147,7 +170,8 @@ static int exynos_boot_secondary(unsigned int cpu, struct task_struct *idle)
 		 * and fall back to boot register if it fails.
 		 */
 		if (call_firmware_op(set_cpu_boot_addr, phys_cpu, boot_addr))
-			__raw_writel(boot_addr, cpu_boot_reg(phys_cpu));
+			if (cpu_boot_reg_base())
+				__raw_writel(boot_addr, cpu_boot_reg(phys_cpu));
 
 		call_firmware_op(cpu_boot, phys_cpu);
 
@@ -205,6 +229,8 @@ static void __init exynos_smp_prepare_cpus(unsigned int max_cpus)
 	if (read_cpuid_part_number() == ARM_CPU_PART_CORTEX_A9)
 		scu_enable(scu_base_addr());
 
+	exynos_smp_prepare_sram();
+
 	/*
 	 * Write the address of secondary startup into the
 	 * system-wide flags register. The boot monitor waits
@@ -222,7 +248,8 @@ static void __init exynos_smp_prepare_cpus(unsigned int max_cpus)
 		boot_addr = virt_to_phys(exynos4_secondary_startup);
 
 		if (call_firmware_op(set_cpu_boot_addr, phys_cpu, boot_addr))
-			__raw_writel(boot_addr, cpu_boot_reg(phys_cpu));
+			if (cpu_boot_reg_base())
+				__raw_writel(boot_addr, cpu_boot_reg(phys_cpu));
 	}
 }
 
Signature · 1 line
1.7.9.5
#1 lore raw

PATCH v2 2/2 Documentation: DT: Exynos: Bind SRAM though DT

Add SRAM binding documentation.

---
Changes since v1:
Minor re-wording for better clarity.

---
 .../devicetree/bindings/arm/exynos/smp-sram.txt    |   38 ++++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/arm/exynos/smp-sram.txt
Documentation/devicetree/bindings/arm/exynos/smp-sram.txt new file +38 -0
new file mode 100644
index 000000000000..c9ff2f58f9b6
@@ -0,0 +1,38 @@
+Samsung Exynos SRAM for SMP bringup:
+------------------------------------
+
+Samsung SMP-capable Exynos SoCs use part of the SRAM for the bringup
+of the secondary cores. Once the core gets powered up it executes the
+code that is residing at some specific location of the SRAM.
+
+Therefore reserved section sub-nodes have to be added to the mmio-sram
+declaration. These nodes are of two types depending upon secure or
+non-secure execution environment.
+
+Required sub-node properties:
+- compatible : depending upon boot mode, should be
+		"samsung,exynos4210-sram" : for Secure SYSRAM
+		"samsung,exynos4210-sram-ns" : for Non-secure SYSRAM
+
+The rest of the properties should follow the generic mmio-sram discription
+found in ../../misc/sram.txt
+
+Example:
+
+	sram at 02020000 {
+		compatible = "mmio-sram";
+		reg = <0x02020000 0x54000>;
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges = <0 0x02020000 0x54000>;
+
+		smp-sram at 0 {
+			compatible = "samsung,exynos4210-sram";
+			reg = <0x0 0x1000>;
+		};
+
+		smp-sram at 53000 {
+			compatible = "samsung,exynos4210-sram-ns";
+			reg = <0x53000 0x1000>;
+		};
+	};
Signature · 1 line
1.7.9.5
#2 lore raw

PATCH v2 2/2 Documentation: DT: Exynos: Bind SRAM though DT

Documentation/devicetree/bindings/arm/exynos/smp-sram.txt line 28

Quoted 7 lines · On Friday 02 May 2014 10:36:20 Sachin Kamat wrote:
Documentation/devicetree/bindings/arm/exynos/smp-sram.txt new file +7 -0
+       sram at 02020000 {
+               compatible = "mmio-sram";
+               reg = <0x02020000 0x54000>;
+               #address-cells = <1>;
+               #size-cells = <1>;
+               ranges = <0 0x02020000 0x54000>;
+

That is actually quite a lot of unused SRAM. Since it came up this morning in another thread, there may be value in using this for coherent DMA allocations for some devices. Not sure about how to best hook this up, but there could be some serious performance improvements. A typical case would be DMA descriptors for a gigabit ethernet adapter, which are a pain to maintain on platforms without cache-coherent DMA.

You could check what drivers you have that call dma_alloc_coherent, and see if any of them are performance-critical, then hack them up to use this memory instead as an experiment.

Arnd

#3 lore raw

PATCH v2 1/2 ARM: EXYNOS: Map SYSRAM through generic SRAM bindings

In reply to Sachin Kamat

Hi Sachin,

The whole series looks quite good, but I have one concern about support for Universal C210 board. Please see my comment inline.

Quoted 50 lines · Sachin Kamat

Instead of hardcoding the SYSRAM details for each SoC, pass this information through device tree (DT) and make the code SoC agnostic. Generic SRAM bindings are used for achieving this.

---
This patch is based on linux next (next-20140501) on top of my Kconfig consolidation patch
http://comments.gmane.org/gmane.linux.kernel.samsung-soc/28642

Changes since v1:
Type and presence of sram nodes is SoC/board dependent. V1 mandated the presence of both the nodes and used to return an error if one of the nodes was absent and thus fail the boot altogether. Removed this dependency.

Tested on 4210/4412 Origen, 5250/5420 Arndale and SMDK5420 boards.

---
  arch/arm/Kconfig                                |    1 +
  arch/arm/boot/dts/exynos4210-universal_c210.dts |   17 ++++++
  arch/arm/boot/dts/exynos4210.dtsi               |   18 +++++++
  arch/arm/boot/dts/exynos4x12.dtsi               |   18 +++++++
  arch/arm/boot/dts/exynos5250.dtsi               |   18 +++++++
  arch/arm/boot/dts/exynos5420.dtsi               |   18 +++++++
  arch/arm/mach-exynos/common.h                   |    1 +
  arch/arm/mach-exynos/exynos.c                   |   64 -----------------------
  arch/arm/mach-exynos/firmware.c                 |    8 ++-
  arch/arm/mach-exynos/include/mach/map.h         |    7 ---
  arch/arm/mach-exynos/platsmp.c                  |   33 ++++++++++--
  11 files changed, 128 insertions(+), 75 deletions(-)
arch/arm/Kconfig +1 -0
index a6aaaad19b1a..f66ea9453df9 100644
@@ -855,6 +855,7 @@ config ARCH_EXYNOS
  	select S5P_DEV_MFC
  	select SAMSUNG_DMADEV
  	select SPARSE_IRQ
+	select SRAM
  	select USE_OF
  	help
  	  Support for SAMSUNG's EXYNOS SoCs (EXYNOS4/5)
arch/arm/boot/dts/exynos4210-universal_c210.dts +0 -0
index 63e34b24b04f..8d4de5c0d0c7 100644

arch/arm/boot/dts/exynos4210-universal_c210.dts line 32

Quoted 5 lines
arch/arm/boot/dts/exynos4210-universal_c210.dts +2 -0
@@ -28,6 +28,23 @@
  		bootargs = "console=ttySAC2,115200N8 root=/dev/mmcblk0p5 rw rootwait earlyprintk panic=5 maxcpus=1";
  	};
 
+	sram at 02020000 {
+		status = "disabled";

Here you just disable just the top level node of non-secure SYSRAM, but the sub-nodes are still present and enabled.

Quoted 18 lines
arch/arm/boot/dts/exynos4210-universal_c210.dts +15 -0
+	};
+
+	sram at 02025000 {
+		compatible = "mmio-sram";
+		reg = <0x02025000 0x1000>;
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges = <0 0x02025000 0x1000>;
+
+		smp-sram at 0 {
+			compatible = "samsung,exynos4210-sram";
+			reg = <0x0 0x1000>;
+		};
+	};
+
  	mct at 10050000 {
  		compatible = "none";
  	};

[snip]

Quoted 14 lines
arch/arm/mach-exynos/platsmp.c +1 -0
index 03e5e9f94705..0aac03204f9f 100644
@@ -20,6 +20,7 @@
  #include <linux/jiffies.h>
  #include <linux/smp.h>
  #include <linux/io.h>
+#include <linux/of_address.h>
 
  #include <asm/cacheflush.h>
  #include <asm/smp_plat.h>
@@ -33,11 +34,33 @@
 

arch/arm/mach-exynos/platsmp.c line 44

Quoted 10 lines
arch/arm/mach-exynos/platsmp.c +8 -0
  extern void exynos4_secondary_startup(void);
 
+static void __iomem *sram_base_addr;
+void __iomem *sram_ns_base_addr;
+
+static void __init exynos_smp_prepare_sram(void)
+{
+	struct device_node *node;
+
+	node = of_find_compatible_node(NULL, NULL, "samsung,exynos4210-sram");

Now here you don't check whether the node is "okay", so on Universal C210 it will pick just the first node with this compatible string,

I think you should be using for_each_compatible_node() here, then check if the node is "okay" using of_devicE_is_available() and only then use this node to map the SYSRAM.

arch/arm/mach-exynos/platsmp.c line 51

Quoted 7 lines
arch/arm/mach-exynos/platsmp.c +7 -0
+	if (node) {
+		sram_base_addr = of_iomap(node, 0);
+		if (!sram_base_addr)
+			pr_err("Secondary CPU boot address not found\n");
+	}
+
+	node = of_find_compatible_node(NULL, NULL, "samsung,exynos4210-sram-ns");

Same here.

Quoted 17 lines
arch/arm/mach-exynos/platsmp.c +8 -1
+	if (node) {
+		sram_ns_base_addr = of_iomap(node, 0);
+		if (!sram_ns_base_addr)
+			pr_err("Secondary CPU boot address not found\n");
+	}
+}
+
  static inline void __iomem *cpu_boot_reg_base(void)
  {
  	if (soc_is_exynos4210() && samsung_rev() == EXYNOS4210_REV_1_1)
  		return S5P_INFORM5;
-	return S5P_VA_SYSRAM;
+	return sram_base_addr;
  }
 
  static inline void __iomem *cpu_boot_reg(int cpu)

arch/arm/mach-exynos/platsmp.c static int exynos_boot_secondary(unsigned int cpu, struct task_struct *idle) · line 173

Quoted 5 lines
arch/arm/mach-exynos/platsmp.c +1 -1
@@ -147,7 +170,8 @@ static int exynos_boot_secondary(unsigned int cpu, struct task_struct *idle)
  		 * and fall back to boot register if it fails.
  		 */
  		if (call_firmware_op(set_cpu_boot_addr, phys_cpu, boot_addr))
-			__raw_writel(boot_addr, cpu_boot_reg(phys_cpu));
+			if (cpu_boot_reg_base())

When can this condition be not met?

Quoted 14 lines
arch/arm/mach-exynos/platsmp.c +3 -0
+				__raw_writel(boot_addr, cpu_boot_reg(phys_cpu));
 
  		call_firmware_op(cpu_boot, phys_cpu);
 
@@ -205,6 +229,8 @@ static void __init exynos_smp_prepare_cpus(unsigned int max_cpus)
  	if (read_cpuid_part_number() == ARM_CPU_PART_CORTEX_A9)
  		scu_enable(scu_base_addr());
 
+	exynos_smp_prepare_sram();
+
  	/*
  	 * Write the address of secondary startup into the
  	 * system-wide flags register. The boot monitor waits

arch/arm/mach-exynos/platsmp.c static void __init exynos_smp_prepare_cpus(unsigned int max_cpus) · line 251

Quoted 5 lines
arch/arm/mach-exynos/platsmp.c +1 -1
@@ -222,7 +248,8 @@ static void __init exynos_smp_prepare_cpus(unsigned int max_cpus)
  		boot_addr = virt_to_phys(exynos4_secondary_startup);
 
  		if (call_firmware_op(set_cpu_boot_addr, phys_cpu, boot_addr))
-			__raw_writel(boot_addr, cpu_boot_reg(phys_cpu));
+			if (cpu_boot_reg_base())

Ditto.

Best regards,
Tomasz

#4 lore raw

PATCH v2 1/2 ARM: EXYNOS: Map SYSRAM through generic SRAM bindings

Hi Tomasz,

Quoted 3 lines · Tomasz Figa

Hi Sachin,

The whole series looks quite good,

Thanks :)

Quoted 63 lines

but I have one concern about support for Universal C210 board. Please see my comment inline.

Quoted 58 lines · Sachin Kamat

Instead of hardcoding the SYSRAM details for each SoC, pass this information through device tree (DT) and make the code SoC agnostic. Generic SRAM bindings are used for achieving this.

---
This patch is based on linux next (next-20140501) on top of my Kconfig consolidation patch
http://comments.gmane.org/gmane.linux.kernel.samsung-soc/28642

Changes since v1:
Type and presence of sram nodes is SoC/board dependent. V1 mandated the presence of both the nodes and used to return an error if one of the nodes was absent and thus fail the boot altogether. Removed this dependency.

Tested on 4210/4412 Origen, 5250/5420 Arndale and SMDK5420 boards.

---
  arch/arm/Kconfig                                |    1 +
  arch/arm/boot/dts/exynos4210-universal_c210.dts |   17 ++++++
  arch/arm/boot/dts/exynos4210.dtsi               |   18 +++++++
  arch/arm/boot/dts/exynos4x12.dtsi               |   18 +++++++
  arch/arm/boot/dts/exynos5250.dtsi               |   18 +++++++
  arch/arm/boot/dts/exynos5420.dtsi               |   18 +++++++
  arch/arm/mach-exynos/common.h                   |    1 +
  arch/arm/mach-exynos/exynos.c                   |   64
-----------------------
  arch/arm/mach-exynos/firmware.c                 |    8 ++-
  arch/arm/mach-exynos/include/mach/map.h         |    7 ---
  arch/arm/mach-exynos/platsmp.c                  |   33 ++++++++++--
  11 files changed, 128 insertions(+), 75 deletions(-)
arch/arm/Kconfig +1 -0
index a6aaaad19b1a..f66ea9453df9 100644
@@ -855,6 +855,7 @@ config ARCH_EXYNOS
        select S5P_DEV_MFC
        select SAMSUNG_DMADEV
        select SPARSE_IRQ
+       select SRAM
        select USE_OF
        help
          Support for SAMSUNG's EXYNOS SoCs (EXYNOS4/5)
arch/arm/boot/dts/exynos4210-universal_c210.dts +0 -0
index 63e34b24b04f..8d4de5c0d0c7 100644
@@ -28,6 +28,23 @@
                bootargs = "console=ttySAC2,115200N8 root=/dev/mmcblk0p5
 rw rootwait earlyprintk panic=5 maxcpus=1";
        };
 
Quoted 6 lines

arch/arm/boot/dts/exynos4210-universal_c210.dts line 32

Quoted 2 lines
arch/arm/boot/dts/exynos4210-universal_c210.dts +2 -0
+       sram at 02020000 {
+               status = "disabled";

Here you just disable just the top level node of non-secure SYSRAM, but the sub-nodes are still present and enabled.

I was under the impression that disabling parent node would also disable the sub-nodes.
I will disable all of them in this case.

Quoted 42 lines
Quoted 20 lines
arch/arm/boot/dts/exynos4210-universal_c210.dts +15 -0
+       };
+
+       sram at 02025000 {
+               compatible = "mmio-sram";
+               reg = <0x02025000 0x1000>;
+               #address-cells = <1>;
+               #size-cells = <1>;
+               ranges = <0 0x02025000 0x1000>;
+
+               smp-sram at 0 {
+                       compatible = "samsung,exynos4210-sram";
+                       reg = <0x0 0x1000>;
+               };
+       };
+
        mct at 10050000 {
                compatible = "none";
        };

[snip]

Quoted 17 lines
arch/arm/mach-exynos/platsmp.c +1 -0
index 03e5e9f94705..0aac03204f9f 100644
@@ -20,6 +20,7 @@
  #include <linux/jiffies.h>
  #include <linux/smp.h>
  #include <linux/io.h>
+#include <linux/of_address.h>
 
  #include <asm/cacheflush.h>
  #include <asm/smp_plat.h>
@@ -33,11 +34,33 @@
 
  extern void exynos4_secondary_startup(void);
 
Quoted 13 lines

arch/arm/mach-exynos/platsmp.c

Quoted 9 lines
arch/arm/mach-exynos/platsmp.c +8 -0
+static void __iomem *sram_base_addr;
+void __iomem *sram_ns_base_addr;
+
+static void __init exynos_smp_prepare_sram(void)
+{
+       struct device_node *node;
+
+       node = of_find_compatible_node(NULL, NULL,
 "samsung,exynos4210-sram");

Now here you don't check whether the node is "okay", so on Universal C210 it will pick just the first node with this compatible string,

Right. Missed that one.

Quoted 4 lines

I think you should be using for_each_compatible_node() here, then check if the node is "okay" using of_devicE_is_available() and only then use this node to map the SYSRAM.

OK.

Quoted 12 lines

arch/arm/mach-exynos/platsmp.c

Quoted 10 lines
arch/arm/mach-exynos/platsmp.c +7 -0
+       if (node) {
+               sram_base_addr = of_iomap(node, 0);
+               if (!sram_base_addr)
+                       pr_err("Secondary CPU boot address not found\n");
+       }
+
+       node = of_find_compatible_node(NULL, NULL,
 "samsung,exynos4210-sram-ns");
Quoted 1 line

Same here.

OK.

Quoted 17 lines
Quoted 17 lines
arch/arm/mach-exynos/platsmp.c +8 -1
+       if (node) {
+               sram_ns_base_addr = of_iomap(node, 0);
+               if (!sram_ns_base_addr)
+                       pr_err("Secondary CPU boot address not found\n");
+       }
+}
+
  static inline void __iomem *cpu_boot_reg_base(void)
  {
        if (soc_is_exynos4210() && samsung_rev() == EXYNOS4210_REV_1_1)
                return S5P_INFORM5;
-       return S5P_VA_SYSRAM;
+       return sram_base_addr;
  }
Quoted 12 lines

arch/arm/mach-exynos/platsmp.c static int exynos_boot_secondary(unsigned int cpu, · line 175

Quoted 9 lines

static inline void __iomem *cpu_boot_reg(int cpu)

arch/arm/mach-exynos/platsmp.c +1 -1
@@ -147,7 +170,8 @@ static int exynos_boot_secondary(unsigned int cpu,
 struct task_struct *idle)
                 * and fall back to boot register if it fails.
                 */
                if (call_firmware_op(set_cpu_boot_addr, phys_cpu,
 boot_addr))
-                       __raw_writel(boot_addr, cpu_boot_reg(phys_cpu));
+                       if (cpu_boot_reg_base())

When can this condition be not met?

I experimented with various combinations of node presence/absence in dts files and in one such case if we do not have the sram-ns node present (on arndale-octa),
the system just hung at boot time (as base address was null) and this check became
necessary.

Quoted 21 lines
Quoted 21 lines
arch/arm/mach-exynos/platsmp.c +1 -0
+                               __raw_writel(boot_addr,
 cpu_boot_reg(phys_cpu));
                call_firmware_op(cpu_boot, phys_cpu);
arch/arm/mach-exynos/platsmp.c +2 -0
@@ -205,6 +229,8 @@ static void __init exynos_smp_prepare_cpus(unsigned
 int max_cpus)
        if (read_cpuid_part_number() == ARM_CPU_PART_CORTEX_A9)
                scu_enable(scu_base_addr());
 
+       exynos_smp_prepare_sram();
+
        /*
         * Write the address of secondary startup into the

* system-wide flags register. The boot monitor waits

arch/arm/mach-exynos/platsmp.c +0 -0
@@ -222,7 +248,8 @@ static void __init exynos_smp_prepare_cpus(unsigned
 int max_cpus)
                boot_addr = virt_to_phys(exynos4_secondary_startup);
 
Quoted 7 lines

arch/arm/mach-exynos/platsmp.c static int exynos_boot_secondary(unsigned int cpu, struct task_struct *idle) · line 173

Quoted 4 lines
arch/arm/mach-exynos/platsmp.c +1 -1
                if (call_firmware_op(set_cpu_boot_addr, phys_cpu,
 boot_addr))
-                       __raw_writel(boot_addr, cpu_boot_reg(phys_cpu));
+                       if (cpu_boot_reg_base())

Ditto.

ditto.

Thanks for your review. Will update the same in v3.

Signature · 2 lines
With warm regards,
Sachin