ARM: rockchip: fix undefined instruction of reset_ctrl_regs

Sometimes the debug module may not work well after resume, since it has
not been correctly reset when wakeup from suspend. That cause system
crash during reusme, and a 'undefined instruction' is displayed on the
console. Set the GRF_FORCE_JTAG bit of RK3288_GRF_SOC_CON0 can ensure
that debug modul is reset. And we can change the value of
RK3288_GRF_SOC_CON0 back when system resume.
Signed-off-by: Chris Zhong <zyw@rock-chips.com>
Tested-by: Caesar Wang <wxt@rock-chips.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>

According to discussions, there does not seem a better solution available.
Please also see the potential security implication described in the
comment inline in the code.
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm/mach-rockchip/pm.c

@@ -44,9 +44,11 @@ static void __iomem *rk3288_bootram_base;
 static phys_addr_t rk3288_bootram_phy;
 
 static struct regmap *pmu_regmap;
+static struct regmap *grf_regmap;
 static struct regmap *sgrf_regmap;
 
 static u32 rk3288_pmu_pwr_mode_con;
+static u32 rk3288_grf_soc_con0;
 static u32 rk3288_sgrf_soc_con0;
 
 static inline u32 rk3288_l2_config(void)
@@ -70,11 +72,25 @@ static void rk3288_slp_mode_set(int level)
 {
 	u32 mode_set, mode_set1;
 
+	regmap_read(grf_regmap, RK3288_GRF_SOC_CON0, &rk3288_grf_soc_con0);
+
 	regmap_read(sgrf_regmap, RK3288_SGRF_SOC_CON0, &rk3288_sgrf_soc_con0);
 
 	regmap_read(pmu_regmap, RK3288_PMU_PWRMODE_CON,
 		    &rk3288_pmu_pwr_mode_con);
 
+	/*
+	 * We need set this bit GRF_FORCE_JTAG here, for the debug module,
+	 * otherwise, it may become inaccessible after resume.
+	 * This creates a potential security issue, as the sdmmc pins may
+	 * accept jtag data for a short time during resume if no card is
+	 * inserted.
+	 * But this is of course also true for the regular boot, before we
+	 * turn of the jtag/sdmmc autodetect.
+	 */
+	regmap_write(grf_regmap, RK3288_GRF_SOC_CON0, GRF_FORCE_JTAG |
+		     GRF_FORCE_JTAG_WRITE);
+
 	/*
 	 * SGRF_FAST_BOOT_EN - system to boot from FAST_BOOT_ADDR
 	 * PCLK_WDT_GATE - disable WDT during suspend.
@@ -135,6 +151,9 @@ static void rk3288_slp_mode_set_resume(void)
 	regmap_write(sgrf_regmap, RK3288_SGRF_SOC_CON0,
 		     rk3288_sgrf_soc_con0 | SGRF_PCLK_WDT_GATE_WRITE
 		     | SGRF_FAST_BOOT_EN_WRITE);
+
+	regmap_write(grf_regmap, RK3288_GRF_SOC_CON0, rk3288_grf_soc_con0 |
+		     GRF_FORCE_JTAG_WRITE);
 }
 
 static int rockchip_lpmode_enter(unsigned long arg)
@@ -193,6 +212,13 @@ static int rk3288_suspend_init(struct device_node *np)
 		return PTR_ERR(pmu_regmap);
 	}
 
+	grf_regmap = syscon_regmap_lookup_by_compatible(
+				"rockchip,rk3288-grf");
+	if (IS_ERR(grf_regmap)) {
+		pr_err("%s: could not find grf regmap\n", __func__);
+		return PTR_ERR(pmu_regmap);
+	}
+
 	sram_np = of_find_compatible_node(NULL, NULL,
 					  "rockchip,rk3288-pmu-sram");
 	if (!sram_np) {

arch/arm/mach-rockchip/pm.h

@@ -48,6 +48,10 @@ static inline void rockchip_suspend_init(void)
 #define RK3288_PMU_WAKEUP_RST_CLR_CNT	0x44
 #define RK3288_PMU_PWRMODE_CON1		0x90
 
+#define RK3288_GRF_SOC_CON0		0x244
+#define GRF_FORCE_JTAG			BIT(12)
+#define GRF_FORCE_JTAG_WRITE		BIT(28)
+
 #define RK3288_SGRF_SOC_CON0		(0x0000)
 #define RK3288_SGRF_FAST_BOOT_ADDR	(0x0120)
 #define SGRF_PCLK_WDT_GATE		BIT(6)