clk: rockchip: clk-cpu: add mux setting for cpu change frequency

In order to improve the main frequency of CPU, the clock path of CPU is
simplified as follows:
                         |--\
                         |   \            |--\
 --apll--|\              |    \           |   \
         | |--apll_core--|     \          |    \
 --24M---|/              |mux1 |--[gate]--|mux2|---clk_core
                         |     /          |    /
 --gpll--|\              |    /    |------|   /
         | |--gpll_core--|   /     |      |--/
 --24M---|/              |--/      |
                                   |
 -------apll_directly--------------|

When the CPU requests high frequency, we want to use MUX2 select the
"apll_directly".
At low frequencies use MUX1 to select “apll_core" and then MUX2 to
select "apll_core_gate".

However, in this way, the CPU frequency conversion needs to be
in the following order:
1. MUX2 select to "apll_core_gate", MUX1 select "gpll_core"
2. Apll sets slow_mode, sets APLL parameters, locks APLL, and then APLL
sets normal_mode
3. MUX1 select "apll_core", MUX2 select "apll_directly"

So add pre_muxs and post_muxs to cover this special requirements.

Change-Id: I944c22f774f5f9c4edaf28099b6c2926076d4749
Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>

drivers/clk/rockchip/clk-cpu.c

@@ -121,6 +121,42 @@ static void rockchip_cpuclk_set_dividers(struct rockchip_cpuclk *cpuclk,
 	}
 }
 
+static void rockchip_cpuclk_set_pre_muxs(struct rockchip_cpuclk *cpuclk,
+					 const struct rockchip_cpuclk_rate_table *rate)
+{
+	int i;
+
+	/* alternate parent is active now. set the pre_muxs */
+	for (i = 0; i < ARRAY_SIZE(rate->pre_muxs); i++) {
+		const struct rockchip_cpuclk_clksel *clksel = &rate->pre_muxs[i];
+
+		if (!clksel->reg)
+			break;
+
+		pr_debug("%s: setting reg 0x%x to 0x%x\n",
+			 __func__, clksel->reg, clksel->val);
+		writel(clksel->val, cpuclk->reg_base + clksel->reg);
+	}
+}
+
+static void rockchip_cpuclk_set_post_muxs(struct rockchip_cpuclk *cpuclk,
+					  const struct rockchip_cpuclk_rate_table *rate)
+{
+	int i;
+
+	/* alternate parent is active now. set the muxs */
+	for (i = 0; i < ARRAY_SIZE(rate->post_muxs); i++) {
+		const struct rockchip_cpuclk_clksel *clksel = &rate->post_muxs[i];
+
+		if (!clksel->reg)
+			break;
+
+		pr_debug("%s: setting reg 0x%x to 0x%x\n",
+			 __func__, clksel->reg, clksel->val);
+		writel(clksel->val, cpuclk->reg_base + clksel->reg);
+	}
+}
+
 static int rockchip_cpuclk_pre_rate_change(struct rockchip_cpuclk *cpuclk,
 					   struct clk_notifier_data *ndata)
 {
@@ -181,6 +217,8 @@ static int rockchip_cpuclk_pre_rate_change(struct rockchip_cpuclk *cpuclk,
 	}
 	rockchip_boost_add_core_div(cpuclk->pll_hw, alt_prate);
 
+	rockchip_cpuclk_set_pre_muxs(cpuclk, rate);
+
 	/* select alternate parent */
 	writel(HIWORD_UPDATE(reg_data->mux_core_alt,
 			     reg_data->mux_core_mask,
@@ -216,6 +254,8 @@ static int rockchip_cpuclk_post_rate_change(struct rockchip_cpuclk *cpuclk,
 			     reg_data->mux_core_shift),
 	       cpuclk->reg_base + reg_data->core_reg);
 
+	rockchip_cpuclk_set_post_muxs(cpuclk, rate);
+
 	/* remove dividers */
 	writel(HIWORD_UPDATE(0, reg_data->div_core_mask,
 			     reg_data->div_core_shift),

drivers/clk/rockchip/clk.h

@@ -430,6 +430,8 @@ struct rockchip_cpuclk_clksel {
 struct rockchip_cpuclk_rate_table {
 	unsigned long prate;
 	struct rockchip_cpuclk_clksel divs[ROCKCHIP_CPUCLK_NUM_DIVIDERS];
+	struct rockchip_cpuclk_clksel pre_muxs[ROCKCHIP_CPUCLK_NUM_DIVIDERS];
+	struct rockchip_cpuclk_clksel post_muxs[ROCKCHIP_CPUCLK_NUM_DIVIDERS];
 };
 
 /**