0001-WIP-allow-first-128KB-of-DRAM-to-be-allocated-static.patch

From bd3a676daae9c94afda2720d2e023312cf2d019d Mon Sep 17 00:00:00 2001
From: Angus Gratton <angus@espressif.com>
Date: Tue, 11 Jul 2017 17:59:02 +0800
Subject: [PATCH] WIP allow first 128KB of DRAM to be allocated statically

- Moves stacks to end of RAM
- Doesn't yet provide a way to block out this RAM from heap
---
 components/bootloader/src/main/bootloader_jump.S   | 55 ++++++++++++++++++++++
 components/bootloader/src/main/bootloader_start.c  | 23 +++++----
 components/bootloader/src/main/esp32.bootloader.ld |  3 +-
 components/esp32/bootstrap_cpu1.S                  | 38 +++++++++++++++
 components/esp32/cpu_start.c                       | 23 +++++----
 5 files changed, 125 insertions(+), 17 deletions(-)
 create mode 100644 components/bootloader/src/main/bootloader_jump.S
 create mode 100644 components/esp32/bootstrap_cpu1.S

diff --git a/components/bootloader/src/main/bootloader_jump.S b/components/bootloader/src/main/bootloader_jump.S
new file mode 100644
index 000000000..3e4b8c04b
--- /dev/null
+++ b/components/bootloader/src/main/bootloader_jump.S
@@ -0,0 +1,55 @@
+// Copyright 2017 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+.data
+.align 4
+bootloader_jump_scratch_space:
+.word 0
+.word 0
+
+.text
+    /* Function to reset the stack pointer to beginning of bootloader bss,
+       and jump to a given entry point function.
+    */
+    .global     bootloader_reset_stack_and_jump_to
+    .type       bootloader_reset_stack_and_jump_to,@function
+    .section ".iram1"
+    .align      4
+bootloader_reset_stack_and_jump_to:
+    entry sp, 16 /* We are called via call8/etc, so need to rotate */
+
+    /* save args */
+    movi a0, bootloader_jump_scratch_space
+    s32i a2, a0, 0 /* dest addr */
+    s32i a3, a0, 4 /* new stack pointer */
+
+    /* Reset register window and clobber registers */
+    movi a0, 1
+    wsr a0, WindowStart
+    movi a0, 0
+    wsr a0, WindowBase
+
+    /* Note: perhaps we should clear some PS fields here? */
+
+    /* reload args */
+    movi a0, bootloader_jump_scratch_space
+    l32i a2, a0, 0 /* dest addr */
+    l32i a3, a0, 4 /* new stack pointer */
+
+    /* initialize a call8-compatible stack, see ISA RM 8.7 */
+    addi sp, a3, -16  /* save area */
+    addi a3, sp, 32 /* 16 past save area */
+    s32e a3, sp, -12 /* write pointer to end of stack */
+    isync
+    jx a2
diff --git a/components/bootloader/src/main/bootloader_start.c b/components/bootloader/src/main/bootloader_start.c
index fd062a5f9..b7b96368f 100644
--- a/components/bootloader/src/main/bootloader_start.c
+++ b/components/bootloader/src/main/bootloader_start.c
@@ -61,7 +61,8 @@ flash cache is down and the app CPU is in reset. We do have a stack, so we can d
 */
 
 
-void bootloader_main();
+static void bootloader_main();
+static void bootloader_call_main() __attribute__((noreturn));
 static void unpack_load_app(const esp_partition_pos_t *app_node);
 void print_flash_info(const esp_image_header_t* pfhdr);
 static void set_cache_and_start_app(uint32_t drom_addr,
@@ -76,6 +77,8 @@ static void clock_configure(void);
 static void uart_console_configure(void);
 static void wdt_reset_check(void);
 
+void bootloader_reset_stack_and_jump_to(void *destination, void *new_top_of_stack) __attribute__((noreturn));
+
 void IRAM_ATTR call_start_cpu0()
 {
     cpu_configure_region_protection();
@@ -106,7 +109,8 @@ void IRAM_ATTR call_start_cpu0()
     DPORT_REG_CLR_BIT(DPORT_PRO_CACHE_CTRL1_REG, DPORT_PRO_CACHE_MASK_DROM0);
     DPORT_REG_CLR_BIT(DPORT_APP_CACHE_CTRL1_REG, DPORT_APP_CACHE_MASK_DROM0);
 
-    bootloader_main();
+    extern int _bootloader_dram_start;
+    bootloader_reset_stack_and_jump_to(bootloader_call_main, &_bootloader_dram_start);
 }
 
 
@@ -228,6 +232,13 @@ static bool ota_select_valid(const esp_ota_select_entry_t *s)
   return s->ota_seq != UINT32_MAX && s->crc == ota_select_crc(s);
 }
 
+static void bootloader_call_main()
+{
+    bootloader_main();
+    ESP_LOGI(TAG, "Halting.");
+    while(1) {}
+}
+
 /**
  *  @function :     bootloader_main
  *  @description:   entry function of 2nd bootloader
@@ -586,12 +597,8 @@ static void set_cache_and_start_app(
     // Application will need to do Cache_Flush(1) and Cache_Read_Enable(1)
 
     ESP_LOGD(TAG, "start: 0x%08x", entry_addr);
-    typedef void (*entry_t)(void);
-    entry_t entry = ((entry_t) entry_addr);
-
-    // TODO: we have used quite a bit of stack at this point.
-    // use "movsp" instruction to reset stack back to where ROM stack starts.
-    (*entry)();
+    /* TODO: use a soc_memory_layout.h constant here instead of 0x400000000... */
+    bootloader_reset_stack_and_jump_to((void *)entry_addr, (void *)0x40000000);
 }
 
 static void update_flash_config(const esp_image_header_t* pfhdr)
diff --git a/components/bootloader/src/main/esp32.bootloader.ld b/components/bootloader/src/main/esp32.bootloader.ld
index 500478814..2557485c2 100644
--- a/components/bootloader/src/main/esp32.bootloader.ld
+++ b/components/bootloader/src/main/esp32.bootloader.ld
@@ -17,7 +17,7 @@ MEMORY
   dport0_seg (RW) :                 	org = 0x3FF00000, len = 0x10		/* IO */
   iram_seg (RWX) :                 	org = 0x40080000, len = 0x400		/* 1k of IRAM used by bootloader functions which need to flush/enable APP CPU cache */ 
   iram_pool_1_seg (RWX) :           org = 0x40078000, len = 0x8000    /* IRAM POOL1, used for APP CPU cache. We can abuse it in bootloader because APP CPU is still held in reset, until we enable APP CPU cache */
-  dram_seg (RW) :                  	org = 0x3FFF0000, len = 0x10000		/* 64k at the end of DRAM, after ROM bootloader stack */
+  dram_seg (RW) :                  	org = 0x3FFFE000, len = 0x2000		/* 8KB at the end of DRAM, after ROM bootloader stack. Can be made bigger if necessary. */
 }
 
 /*  Default entry point:  */
@@ -48,6 +48,7 @@ SECTIONS
   .dram0.bss (NOLOAD) :
   {
     . = ALIGN (8);
+    _bootloader_dram_start = ABSOLUTE(.);
     _bss_start = ABSOLUTE(.);
     *(.dynsbss)
     *(.sbss)
diff --git a/components/esp32/bootstrap_cpu1.S b/components/esp32/bootstrap_cpu1.S
new file mode 100644
index 000000000..9ca0ef6f7
--- /dev/null
+++ b/components/esp32/bootstrap_cpu1.S
@@ -0,0 +1,38 @@
+// Copyright 2017 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+.extern call_start_cpu1
+.extern cpu1_stack_end
+
+    /* Function to set the CPU1 stack pointer to cpu1_stack_end,
+       then jump to a given entry point function.
+    */
+    .global     bootstrap_cpu1
+    .type       bootstrap_cpu1,@function
+    .align      4
+bootstrap_cpu1:
+    /* Reset register window and clobber registers */
+    movi a0, 1
+    wsr a0, WindowStart
+    movi a0, 0
+    wsr a0, WindowBase
+
+    movi a0, cpu1_stack_end
+    l32i a0, a0, 0
+    addi sp, a0, -16  /* save area */
+    addi a0, sp, 32 /* 16 past save area */
+    s32e a0, sp, -12 /* write pointer to end of stack */
+    isync
+    j call_start_cpu1
+
diff --git a/components/esp32/cpu_start.c b/components/esp32/cpu_start.c
index 858036c67..4085a2670 100644
--- a/components/esp32/cpu_start.c
+++ b/components/esp32/cpu_start.c
@@ -68,12 +68,12 @@
 #define STRINGIFY(s) STRINGIFY2(s)
 #define STRINGIFY2(s) #s
 
-void start_cpu0(void) __attribute__((weak, alias("start_cpu0_default")));
-void start_cpu0_default(void) IRAM_ATTR;
+void start_cpu0(void) __attribute__((weak, alias("start_cpu0_default"))) __attribute__((noreturn));
+void start_cpu0_default(void) IRAM_ATTR __attribute__((noreturn));
 #if !CONFIG_FREERTOS_UNICORE
-static void IRAM_ATTR call_start_cpu1();
-void start_cpu1(void) __attribute__((weak, alias("start_cpu1_default")));
-void start_cpu1_default(void) IRAM_ATTR;
+void IRAM_ATTR call_start_cpu1() __attribute__((noreturn));
+void start_cpu1(void) __attribute__((weak, alias("start_cpu1_default"))) __attribute__((noreturn));
+void start_cpu1_default(void) IRAM_ATTR __attribute__((noreturn));
 static bool app_cpu_started = false;
 #endif //!CONFIG_FREERTOS_UNICORE
 
@@ -90,6 +90,9 @@ extern void (*__init_array_start)(void);
 extern void (*__init_array_end)(void);
 extern volatile int port_xSchedulerRunning[2];
 
+/* TODO: use a constant in soc_memory_layout.h for this not hardcoded */
+uint32_t cpu1_stack_end = 0x3fff8000;
+
 static const char* TAG = "cpu_start";
 
 /*
@@ -97,7 +100,7 @@ static const char* TAG = "cpu_start";
  * and the app CPU is in reset. We do have a stack, so we can do the initialization in C.
  */
 
-void IRAM_ATTR call_start_cpu0()
+void IRAM_ATTR __attribute__((noreturn)) call_start_cpu0()
 {
 #if CONFIG_FREERTOS_UNICORE
     RESET_REASON rst_reas[1];
@@ -137,7 +140,8 @@ void IRAM_ATTR call_start_cpu0()
     ESP_EARLY_LOGI(TAG, "Pro cpu up.");
 
 #if !CONFIG_FREERTOS_UNICORE
-    ESP_EARLY_LOGI(TAG, "Starting app cpu, entry point is %p", call_start_cpu1);
+    extern void bootstrap_cpu1(void); /* asm function, calls call_start_cpu1() */
+    ESP_EARLY_LOGI(TAG, "Starting app cpu, entry point is %p -> %p", call_start_cpu1, bootstrap_cpu1);
     //Flush and enable icache for APP CPU
     Cache_Flush(1);
     Cache_Read_Enable(1);
@@ -152,7 +156,7 @@ void IRAM_ATTR call_start_cpu0()
         DPORT_SET_PERI_REG_MASK(DPORT_APPCPU_CTRL_A_REG, DPORT_APPCPU_RESETTING);
         DPORT_CLEAR_PERI_REG_MASK(DPORT_APPCPU_CTRL_A_REG, DPORT_APPCPU_RESETTING);
     }
-    ets_set_appcpu_boot_addr((uint32_t)call_start_cpu1);
+    ets_set_appcpu_boot_addr((intptr_t)&bootstrap_cpu1);
 
     while (!app_cpu_started) {
         ets_delay_us(100);
@@ -182,6 +186,7 @@ static void wdt_reset_cpu1_info_enable(void)
     DPORT_REG_CLR_BIT(DPORT_APP_CPU_RECORD_CTRL_REG, DPORT_APP_CPU_RECORD_ENABLE);
 }
 
+/* called from bootstrap_cpu1() */
 void IRAM_ATTR call_start_cpu1()
 {
     asm volatile (\
@@ -287,6 +292,7 @@ void start_cpu0_default(void)
             ESP_TASK_MAIN_PRIO, NULL, 0);
     ESP_LOGI(TAG, "Starting scheduler on PRO CPU.");
     vTaskStartScheduler();
+    abort(); /* abort() here indicates there wasn't enough free memory to start scheduler */
 }
 
 #if !CONFIG_FREERTOS_UNICORE
@@ -313,6 +319,7 @@ void start_cpu1_default(void)
 
     ESP_EARLY_LOGI(TAG, "Starting scheduler on APP CPU.");
     xPortStartScheduler();
+    abort(); /* abort() here indicates something went wrong starting scheduler */
 }
 #endif //!CONFIG_FREERTOS_UNICORE
 
-- 
2.13.2