clk: rockchip: protect critical clocks from getting disabled

The clock-tree contains clocks that should never get disabled automatically.
One example are the base ACLKs, the base supplies for all peripherals.

Therefore add a structure similar to the sunxi clock-tree to protect these
special clocks from being disabled.
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Doug Anderson <dianders@chromium.org>
Tested-by: Kever Yang <kever.yang@rock-chips.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

drivers/clk/rockchip/clk-rk3188.c

@@ -599,6 +599,11 @@ static struct rockchip_clk_branch rk3188_clk_branches[] __initdata = {
 	GATE(ACLK_GPS, "aclk_gps", "aclk_peri", 0, RK2928_CLKGATE_CON(8), 13, GFLAGS),
 };
 
+static const char *rk3188_critical_clocks[] __initconst = {
+	"aclk_cpu",
+	"aclk_peri",
+};
+
 static void __init rk3188_common_clk_init(struct device_node *np)
 {
 	void __iomem *reg_base;
@@ -628,6 +633,8 @@ static void __init rk3188_common_clk_init(struct device_node *np)
 				   RK3188_GRF_SOC_STATUS);
 	rockchip_clk_register_branches(common_clk_branches,
 				  ARRAY_SIZE(common_clk_branches));
+	rockchip_clk_protect_critical(rk3188_critical_clocks,
+				      ARRAY_SIZE(rk3188_critical_clocks));
 
 	rockchip_register_softrst(np, 9, reg_base + RK2928_SOFTRST_CON(0),
 				  ROCKCHIP_SOFTRST_HIWORD_MASK);

drivers/clk/rockchip/clk-rk3288.c

@@ -680,6 +680,11 @@ static struct rockchip_clk_branch rk3288_clk_branches[] __initdata = {
 	GATE(0, "pclk_isp_in", "ext_isp", 0, RK3288_CLKGATE_CON(16), 3, GFLAGS),
 };
 
+static const char *rk3288_critical_clocks[] __initconst = {
+	"aclk_cpu",
+	"aclk_peri",
+};
+
 static void __init rk3288_clk_init(struct device_node *np)
 {
 	void __iomem *reg_base;
@@ -710,6 +715,8 @@ static void __init rk3288_clk_init(struct device_node *np)
 				   RK3288_GRF_SOC_STATUS);
 	rockchip_clk_register_branches(rk3288_clk_branches,
 				  ARRAY_SIZE(rk3288_clk_branches));
+	rockchip_clk_protect_critical(rk3288_critical_clocks,
+				      ARRAY_SIZE(rk3288_critical_clocks));
 
 	rockchip_register_softrst(np, 9, reg_base + RK3288_SOFTRST_CON(0),
 				  ROCKCHIP_SOFTRST_HIWORD_MASK);

drivers/clk/rockchip/clk.c

@@ -296,3 +296,16 @@ void __init rockchip_clk_register_branches(
 		rockchip_clk_add_lookup(clk, list->id);
 	}
 }
+
+void __init rockchip_clk_protect_critical(const char *clocks[], int nclocks)
+{
+	int i;
+
+	/* Protect the clocks that needs to stay on */
+	for (i = 0; i < nclocks; i++) {
+		struct clk *clk = __clk_lookup(clocks[i]);
+
+		if (clk)
+			clk_prepare_enable(clk);
+	}
+}

drivers/clk/rockchip/clk.h

@@ -329,6 +329,7 @@ void rockchip_clk_register_branches(struct rockchip_clk_branch *clk_list,
 				    unsigned int nr_clk);
 void rockchip_clk_register_plls(struct rockchip_pll_clock *pll_list,
 				unsigned int nr_pll, int grf_lock_offset);
+void rockchip_clk_protect_critical(const char *clocks[], int nclocks);
 
 #define ROCKCHIP_SOFTRST_HIWORD_MASK	BIT(0)