[PATCH v2] clk: rockchip: switch PLLs to slow mode before reboot for rk3288

[Chris Zhong]

We've been seeing some crashes at reboot test on rk3288-based systems,
which boards have not reset pin connected to NPOR, they reboot by
setting 0xfdb9 to RK3288_GLB_SRST_FST register. If the APLL works in
a high frequency mode, some IPs might hang during soft reset.
It appears that we can fix the problem by switching to slow mode before
reboot, just like what we did before suspend.

Signed-off-by: Chris Zhong <zyw at rock-chips.com>

---

Changes in v2:
replace restart_handlers with the shutdown callback of syscore

 drivers/clk/rockchip/clk-rk3288.c | 36 +++++++++++++++++++-----------------
 1 file changed, 19 insertions(+), 17 deletions(-)

diff --git a/drivers/clk/rockchip/clk-rk3288.c b/drivers/clk/rockchip/clk-rk3288.c
index 9040878..5ce44af 100644
--- a/drivers/clk/rockchip/clk-rk3288.c
+++ b/drivers/clk/rockchip/clk-rk3288.c
@@ -16,6 +16,7 @@
 #include <linux/clk-provider.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
+#include <linux/reboot.h>
 #include <linux/syscore_ops.h>
 #include <dt-bindings/clock/rk3288-cru.h>
 #include "clk.h"
@@ -783,9 +784,9 @@ static const char *const rk3288_critical_clocks[] __initconst = {
 	"pclk_pd_pmu",
 };
 
-#ifdef CONFIG_PM_SLEEP
 static void __iomem *rk3288_cru_base;
 
+#ifdef CONFIG_PM_SLEEP
 /* Some CRU registers will be reset in maskrom when the system
  * wakes up from fastboot.
  * So save them before suspend, restore them after resume.
@@ -839,34 +840,32 @@ static void rk3288_clk_resume(void)
 			       rk3288_cru_base + reg_id);
 	}
 }
+#endif
 
-static struct syscore_ops rk3288_clk_syscore_ops = {
-	.suspend = rk3288_clk_suspend,
-	.resume = rk3288_clk_resume,
-};
-
-static void rk3288_clk_sleep_init(void __iomem *reg_base)
+static void rk3288_clk_shutdown(void)
 {
-	rk3288_cru_base = reg_base;
-	register_syscore_ops(&rk3288_clk_syscore_ops);
+	writel_relaxed(0xf3030000, rk3288_cru_base + RK3288_MODE_CON);
 }
 
-#else /* CONFIG_PM_SLEEP */
-static void rk3288_clk_sleep_init(void __iomem *reg_base) {}
+static struct syscore_ops rk3288_clk_syscore_ops = {
+#ifdef CONFIG_PM_SLEEP
+	.suspend = rk3288_clk_suspend,
+	.resume = rk3288_clk_resume,
 #endif
+	.shutdown = rk3288_clk_shutdown,
+};
 
 static void __init rk3288_clk_init(struct device_node *np)
 {
-	void __iomem *reg_base;
 	struct clk *clk;
 
-	reg_base = of_iomap(np, 0);
-	if (!reg_base) {
+	rk3288_cru_base = of_iomap(np, 0);
+	if (!rk3288_cru_base) {
 		pr_err("%s: could not map cru region\n", __func__);
 		return;
 	}
 
-	rockchip_clk_init(np, reg_base, CLK_NR_CLKS);
+	rockchip_clk_init(np, rk3288_cru_base, CLK_NR_CLKS);
 
 	/* xin12m is created by an cru-internal divider */
 	clk = clk_register_fixed_factor(NULL, "xin12m", "xin24m", 0, 1, 2);
@@ -907,10 +906,13 @@ static void __init rk3288_clk_init(struct device_node *np)
 			&rk3288_cpuclk_data, rk3288_cpuclk_rates,
 			ARRAY_SIZE(rk3288_cpuclk_rates));
 
-	rockchip_register_softrst(np, 12, reg_base + RK3288_SOFTRST_CON(0),
+	rockchip_register_softrst(np, 12,
+				  rk3288_cru_base + RK3288_SOFTRST_CON(0),
 				  ROCKCHIP_SOFTRST_HIWORD_MASK);
 
 	rockchip_register_restart_notifier(RK3288_GLB_SRST_FST);
-	rk3288_clk_sleep_init(reg_base);
+
+	register_syscore_ops(&rk3288_clk_syscore_ops);
+;
 }
 CLK_OF_DECLARE(rk3288_cru, "rockchip,rk3288-cru", rk3288_clk_init);
-- 
2.6.3