flash: Add new stm32h7x driver support

Add basic support for:
     -STM32H7x (Embedded flash 2M)

Erase and write tested on stm32h743.

Change-Id: Ie8d8786227cdeee39fcf5663167a053ad8dcef4c
Signed-off-by: Rémi Prud'homme <remi.prudhomme@st.com>
Signed-off-by: Alexandre TORGUE <alexandre.torgue@st.com>
Reviewed-on: http://openocd.zylin.com/4181
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

1 files changed, 121 insertions, 0 deletions

diff --git a/contrib/loaders/flash/stm32h7x.S b/contrib/loaders/flash/stm32h7x.S
new file mode 100644
index 0000000..0f5ea99
--- /dev/null
+++ b/contrib/loaders/flash/stm32h7x.S
@@ -0,0 +1,121 @@
+/***************************************************************************
+ *   Copyright (C) 2017 by STMicroelectronics                              *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, write to the                         *
+ *   Free Software Foundation, Inc.                                        *
+ ***************************************************************************/
+
+	.text
+	.syntax unified
+	.cpu cortex-m7
+	.thumb
+	.thumb_func
+
+/*
+ * To assemble:
+ * arm-none-eabi-gcc -c stm32h7x.S
+ *
+ * To disassemble:
+ * arm-none-eabi-objdump -d stm32h7x.o
+ *
+ * To generate binary file:
+ * arm-none-eabi-objcopy -O binary stm32h7x.o stm32h7_flash_write_code.bin
+ *
+ * To generate include file:
+ * xxd -i stm32h7_flash_write_code.bin
+ */
+
+/*
+ * Code limitations:
+ * The workarea must have size multiple of 4 bytes, since R/W
+ * operations are all at 32 bits.
+ * The workarea must be big enough to contain 32 bytes of data,
+ * thus the minimum size is (rp, wp, data) = 4 + 4 + 32 = 40 bytes.
+ * To benefit from concurrent host write-to-buffer and target
+ * write-to-flash, the workarea must be way bigger than the minimum.
+ */
+
+/*
+ * Params :
+ * r0 = workarea start, status (out)
+ * r1 = workarea end
+ * r2 = target address
+ * r3 = count (256 bit words)
+ * r4 = flash reg base
+ *
+ * Clobbered:
+ * r5 - rp
+ * r6 - wp, status, tmp
+ * r7 - loop index, tmp
+ */
+
+#define STM32_FLASH_CR_OFFSET	0x0C	/* offset of CR register in FLASH struct */
+#define STM32_FLASH_SR_OFFSET	0x10	/* offset of SR register in FLASH struct */
+#define STM32_CR_PROG			0x00000032	/* PSIZE64 | PG */
+#define STM32_SR_BUSY_MASK		0x00000001	/* BSY */
+#define STM32_SR_ERROR_MASK		0x03ee0000	/* DBECCERR | SNECCERR | RDSERR | RDPERR | OPERR
+											   | INCERR | STRBERR | PGSERR | WRPERR */
+
+code:
+	ldr		r5, [r0, #4]		/* read rp */
+
+wait_fifo:
+	ldr		r6, [r0, #0]		/* read wp */
+	cbz		r6, exit			/* abort if wp == 0, status = 0 */
+	subs	r6, r6, r5			/* number of bytes available for read in r6 */
+	ittt	mi					/* if wrapped around */
+	addmi	r6, r1				/* add size of buffer */
+	submi	r6, r0
+	submi	r6, #8
+	cmp		r6, #32				/* wait until 32 bytes are available */
+	bcc		wait_fifo
+
+	mov		r6, #STM32_CR_PROG
+	str		r6, [r4, #STM32_FLASH_CR_OFFSET]
+
+	mov		r7, #8				/* program by 8 words = 32 bytes */
+write_flash:
+	ldr		r6, [r5], #0x04		/* read one word from src, increment ptr */
+	str		r6, [r2], #0x04		/* write one word to dst, increment ptr */
+	dsb
+	cmp		r5, r1				/* if rp >= end of buffer ... */
+	it		cs
+	addcs	r5, r0, #8			/* ... then wrap at buffer start */
+	subs	r7, r7, #1			/* decrement loop index */
+	bne		write_flash			/* loop if not done */
+
+busy:
+	ldr		r6, [r4, #STM32_FLASH_SR_OFFSET]
+	tst		r6, #STM32_SR_BUSY_MASK
+	bne		busy				/* operation in progress, wait ... */
+
+	ldr		r7, stm32_sr_error_mask
+	tst		r6, r7
+	bne		error				/* fail... */
+
+	str		r5, [r0, #4]		/* store rp */
+	subs	r3, r3, #1			/* decrement count */
+	bne		wait_fifo			/* loop if not done */
+	b		exit
+
+error:
+	movs	r7, #0
+	str		r7, [r0, #4]		/* set rp = 0 on error */
+
+exit:
+	mov		r0, r6				/* return status in r0 */
+	bkpt	#0x00
+
+stm32_sr_error_mask:
+	.word	STM32_SR_ERROR_MASK