RT106081: U-Boot STM32F7. Use 'dmamem' atag to pass kern dmamem area

Note, 'dmamem' is now allocated (and then reserved in linux) before
the middle of the SDRAM. This is to be able to run rather big (~6MB)
'qt' app in linux then.
Signed-off-by: Yuri Tikhonov <yur@emcraft.com>

cpu/arm_cortexm3/stm32/soc.c

@@ -191,6 +191,17 @@ static void stm32f7_mpu_config(void)
 #endif
 		0 <<  8 | 24 <<  1 | 1 <<  0);
 
+#if defined(CONFIG_STM32F7_DCACHE_ON)
+	/*
+	 * Configure DMAMEM as non-cacheable
+	 */
+	cortex_m3_mpu_set_region(MPU_RGN_SDRAM_NC,
+		CONFIG_DMAMEM_BASE | 1 << 4 | MPU_RGN_SDRAM_NC << 0,
+		0 << 28 | 3 << 24 |
+		1 << 19 | 0 << 18 | 0 << 17 | 0 << 16 |
+		0 <<  8 | ((ffs(CONFIG_DMAMEM_SZ_ALL) - 2) <<  1) | 1 <<  0);
+#endif
+
 #if defined(CONFIG_STM32F7_DCACHE_ON) || defined(CONFIG_STM32F7_ICACHE_ON)
 	stm32f7_envm_mpu_cfg(0, 0);
 #endif
@@ -202,40 +213,6 @@ static void stm32f7_mpu_config(void)
 	cortex_m3_mpu_enable(1);
 }
 
-#if defined(CONFIG_STM32F7_DCACHE_ON)
-/*
- * Use 'dmamem' from cmdline passed to kernel to configure non-cacheable
- * region appropriately ('dmamem' is in MB)
- */
-void arch_preboot_os(void)
-{
-	char	buf[256], *s, *e;
-	char	*cmdline = getenv ("bootargs");
-	int	dmamem = 0;
-
-	if (!cmdline)
-		return;
-	s = strstr(cmdline, "dmamem=");
-	if (!s)
-		return;
-	s += strlen("dmamem=");
-	e = strchr(s, ' ');
-	strncpy(buf, s, e - s);
-	dmamem = simple_strtoul(buf, NULL, 10);
-	if (!dmamem)
-		return;
-
-	cortex_m3_mpu_enable(0);
-	cortex_m3_mpu_set_region(MPU_RGN_SDRAM_NC,
-		(CONFIG_SYS_RAM_BASE + CONFIG_SYS_RAM_SIZE -
-		 (dmamem * 1024 * 1024)) | 1 << 4 | MPU_RGN_SDRAM_NC << 0,
-		0 << 28 | 3 << 24 |
-		1 << 19 | 0 << 18 | 0 << 17 | 0 << 16 |
-		0 <<  8 | ((ffs(dmamem) + 18) <<  1) | 1 <<  0);
-	cortex_m3_mpu_enable(1);
-}
-#endif
-
 #if defined(CONFIG_STM32F7_ICACHE_ON) || defined(CONFIG_STM32F7_DCACHE_ON)
 /*
  * Enable Data and/or Instruction caches

include/asm-arm/setup.h

@@ -188,6 +188,15 @@ struct tag_cmdline {
 	char	cmdline[1];	/* this is the minimum size */
 };
 
+/* dmamem parameters, all must be PAGE_SIZE aligned */
+#define ATAG_DMAMEM     0x5441000A
+
+struct tag_dmamem {
+	unsigned long	base;	/* base address of dmamem */
+	unsigned long	sz_all;	/* size of dmamem */
+	unsigned long	sz_fb;	/* size of fb at start of dmamem */
+};
+
 /* acorn RiscPC specific information */
 #define ATAG_ACORN	0x41000101
 
@@ -217,6 +226,7 @@ struct tag {
 		struct tag_revision	revision;
 		struct tag_videolfb	videolfb;
 		struct tag_cmdline	cmdline;
+		struct tag_dmamem	dmamem;
 
 		/*
 		 * Acorn specific

include/configs/stm32f7-som.h

@@ -120,10 +120,19 @@
 #define CONFIG_STM32F7_DCACHE_ON
 /* #undef CONFIG_STM32F7_DCACHE_ON */
 
-#ifdef CONFIG_STM32F7_DCACHE_ON
-# define CONFIG_DMAMEM_SIZE		1	/* 1MB, must be a pwr of 2 */
-#else
-# define CONFIG_DMAMEM_SIZE		0
+/*
+ * Actually we don't need DMAMEM if DCACHE is off. But we
+ * want to be able to run the same kernel image with or
+ * without DCACHE. So, pass DMAMEM tag always.
+ * Note, SZ_ALL must be power of 2 (to program MPU correctly)!
+ */
+#define CONFIG_DMAMEM_TAG
+#if defined(CONFIG_DMAMEM_TAG)
+# define CONFIG_DMAMEM_SZ_ALL		(1 << 20)	/* 1MB */
+# define CONFIG_DMAMEM_SZ_FB		(640 * 1024)
+# define CONFIG_DMAMEM_BASE		(CONFIG_SYS_RAM_BASE + \
+					 (CONFIG_SYS_RAM_SIZE / 2) - \
+					 CONFIG_DMAMEM_SZ_ALL)
 #endif
 
 #define CONFIG_ARMCORTEXM3_SOC_INIT
@@ -339,8 +348,7 @@
 /* boot args and env */
 #define CONFIG_HOSTNAME			stm32f7-som
 #define CONFIG_BOOTARGS			"stm32_platform=stm32f7-som "	\
-					"console=ttyS0,115200 panic=10 "\
-					"dmamem=" MK_STR(CONFIG_DMAMEM_SIZE)
+					"console=ttyS0,115200 panic=10"
 
 #define LOADADDR			"0xC0007FC0"
 

lib_arm/bootm.c

@@ -35,7 +35,8 @@ DECLARE_GLOBAL_DATA_PTR;
     defined (CONFIG_SERIAL_TAG) || \
     defined (CONFIG_REVISION_TAG) || \
     defined (CONFIG_VFD) || \
-    defined (CONFIG_LCD)
+    defined (CONFIG_LCD) || \
+    defined (CONFIG_DMAMEM_TAG)
 static void setup_start_tag (bd_t *bd);
 
 # ifdef CONFIG_SETUP_MEMORY_TAGS
@@ -53,6 +54,10 @@ static void setup_end_tag (bd_t *bd);
 static void setup_videolfb_tag (gd_t *gd);
 # endif
 
+# ifdef CONFIG_DMAMEM_TAG
+static void setup_dmamem_tag (void);
+# endif
+
 static struct tag *params;
 #endif /* CONFIG_SETUP_MEMORY_TAGS || CONFIG_CMDLINE_TAG || CONFIG_INITRD_TAG */
 
@@ -89,7 +94,8 @@ int do_bootm_linux(int flag, int argc, char *argv[], bootm_headers_t *images)
     defined (CONFIG_SERIAL_TAG) || \
     defined (CONFIG_REVISION_TAG) || \
     defined (CONFIG_LCD) || \
-    defined (CONFIG_VFD)
+    defined (CONFIG_VFD) || \
+    defined (CONFIG_DMAMEM_TAG)
 	setup_start_tag (bd);
 #ifdef CONFIG_SERIAL_TAG
 	setup_serial_tag (&params);
@@ -109,6 +115,9 @@ int do_bootm_linux(int flag, int argc, char *argv[], bootm_headers_t *images)
 #endif
 #if defined (CONFIG_VFD) || defined (CONFIG_LCD)
 	setup_videolfb_tag ((gd_t *) gd);
+#endif
+#ifdef CONFIG_DMAMEM_TAG
+	setup_dmamem_tag();
 #endif
 	setup_end_tag (bd);
 #endif
@@ -285,6 +294,18 @@ void setup_revision_tag(struct tag **in_params)
 }
 #endif  /* CONFIG_REVISION_TAG */
 
+#ifdef CONFIG_DMAMEM_TAG
+void setup_dmamem_tag (void)
+{
+	params->hdr.tag = ATAG_DMAMEM;
+	params->hdr.size = tag_size(tag_dmamem);
+	params->u.dmamem.base = CONFIG_DMAMEM_BASE;
+	params->u.dmamem.sz_all = CONFIG_DMAMEM_SZ_ALL;
+	params->u.dmamem.sz_fb = CONFIG_DMAMEM_SZ_FB;
+	params = tag_next(params);
+}
+#endif
+
 
 static void setup_end_tag (bd_t *bd)
 {