关于RK3506 的MCU软复位后跑不起问题

官方SDK在系统不断电软复位时mcu起不来，原因是在配置入口地址前没有去写MCU和总线复位。这里修改一下MCU启动时序。

1. 先通过 PMU 将 mcu_rst_dis_cfg 置 0（assert PMU 侧复位，系统级复位，高优先级）
2. 再通过 CRU SOFTRST_CON5 bit10 assert 复位 （CRU逻辑复位，总线复位。）
3. 配置入口地址（sip_smc_mcu_config）
4. 开时钟
5. 配置 stcalib
6. 先释放 CRU 复位（SOFTRST_CON5 bit10=0）
7. 最后通过 PMU 将 mcu_rst_dis_cfg 置 1（release PMU 侧复位，MCU 开始运行）

下面是uboot(arch/arm/mach-rockchip/rk3506/rk3506.c)改动点：

int fit_standalone_release(char *id, uintptr_t entry_point)
{
	/*
	 * MCU reset is controlled by two independent sources that must both
	 * be asserted before reconfiguring the entry address:
	 *
	 * 1. PMU_INT_MASK_CON[2] mcu_rst_dis_cfg (0xFF90000C):
	 *    0 = assert MCU reset, 1 = release MCU reset
	 *    On soft-reboot this bit is still 1 (release), so we must
	 *    explicitly drive it to 0 first.
	 *
	 * 2. CRU SOFTRST_CON5[10] hresetn_m0 (0xFF9A0A14):
	 *    1 = assert reset, 0 = release reset (standard RW with write-mask)
	 *
	 * Sequence: assert both resets → configure entry → enable clocks →
	 *           release CRU reset → release PMU reset (MCU starts here).
	 */

	/* Assert PMU MCU reset (mcu_rst_dis_cfg=0, write-mask bit2=1) */
	writel(0x00040000, PMU_BASE + PMU_INT_MASK_CON);

	/* Assert CRU bus M0 reset (hresetn_m0=1, write-mask bit10=1) */
	writel(0x04000400, CRU_BASE + CRU_SOFTRST_CON5);
	udelay(10);

	/* Configure MCU address map: map 0 to entry_point via ATF */
	sip_smc_mcu_config(ROCKCHIP_SIP_CONFIG_BUSMCU_0_ID,
		ROCKCHIP_SIP_CONFIG_MCU_CODE_START_ADDR,
		entry_point);

	/* Enable bus M0 clocks: swclktck_m0 (bit11=0) and hclk_m0 (bit10=0) */
	writel(0x0c000000, CRU_BASE + CRU_GATE_CON5);
	writel(0xe0000000, CRU_BASE + CRU_GATE_CON6);

	/* Set M0 system time calibration (GRF_SOC_CON36 grf_con_m0_stalib) */
	writel(0xbcd3d80, 0xff288090);

	/* Release CRU bus M0 reset (hresetn_m0=0, write-mask bit10=1) */
	writel(0x04000000, CRU_BASE + CRU_SOFTRST_CON5);
	udelay(10);

	/*
	 * Release PMU MCU reset and unmask MCU global interrupt
	 * (mcu_rst_dis_cfg=1, glb_int_mask_mcu=0, write-mask bits 2:1=1)
	 * MCU begins execution from entry_point after this write.
	 */
	writel(0x00060004, PMU_BASE + PMU_INT_MASK_CON);

	return 0;
}