cpufreq: imx: update the clock switch flow to support imx6ul

For i.MX6UL, the clock switch flow is slightly different from
other i.MX6 SOCs. It has a 'secondary_sel' clk that will be used
when the CPU freq is higher than 396MHz. So the clock switch flow in
'set_target' callback need to update to support i.MX6UL in the common
i.MX6 SOC cpufreq driver.

Signed-off-by: Bai Ping <b51503@freescale.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/cpufreq/imx6q-cpufreq.c b/drivers/cpufreq/imx6q-cpufreq.c
index 380a90d3c57edda0d3e81eeeff60e01e64a0ba7b..9b4a7bd04dea283f21e2b4fd6b1b95731dcb05ad 100644 (file)
--- a/drivers/cpufreq/imx6q-cpufreq.c
+++ b/drivers/cpufreq/imx6q-cpufreq.c
@@ -30,6 +30,10 @@ static struct clk *pll1_sw_clk;
 static struct clk *step_clk;
 static struct clk *pll2_pfd2_396m_clk;
 
+/* clk used by i.MX6UL */
+static struct clk *pll2_bus_clk;
+static struct clk *secondary_sel_clk;
+
 static struct device *cpu_dev;
 static bool free_opp;
 static struct cpufreq_frequency_table *freq_table;
@@ -91,16 +95,36 @@ static int imx6q_set_target(struct cpufreq_policy *policy, unsigned int index)
         * The setpoints are selected per PLL/PDF frequencies, so we need to
         * reprogram PLL for frequency scaling.  The procedure of reprogramming
         * PLL1 is as below.
-        *
+        * For i.MX6UL, it has a secondary clk mux, the cpu frequency change
+        * flow is slightly different from other i.MX6 OSC.
+        * The cpu frequeny change flow for i.MX6(except i.MX6UL) is as below:
         *  - Enable pll2_pfd2_396m_clk and reparent pll1_sw_clk to it
         *  - Reprogram pll1_sys_clk and reparent pll1_sw_clk back to it
         *  - Disable pll2_pfd2_396m_clk
         */
-       clk_set_parent(step_clk, pll2_pfd2_396m_clk);
-       clk_set_parent(pll1_sw_clk, step_clk);
-       if (freq_hz > clk_get_rate(pll2_pfd2_396m_clk)) {
-               clk_set_rate(pll1_sys_clk, new_freq * 1000);
+       if (of_machine_is_compatible("fsl,imx6ul")) {
+               /*
+                * When changing pll1_sw_clk's parent to pll1_sys_clk,
+                * CPU may run at higher than 528MHz, this will lead to
+                * the system unstable if the voltage is lower than the
+                * voltage of 528MHz, so lower the CPU frequency to one
+                * half before changing CPU frequency.
+                */
+               clk_set_rate(arm_clk, (old_freq >> 1) * 1000);
                clk_set_parent(pll1_sw_clk, pll1_sys_clk);
+               if (freq_hz > clk_get_rate(pll2_pfd2_396m_clk))
+                       clk_set_parent(secondary_sel_clk, pll2_bus_clk);
+               else
+                       clk_set_parent(secondary_sel_clk, pll2_pfd2_396m_clk);
+               clk_set_parent(step_clk, secondary_sel_clk);
+               clk_set_parent(pll1_sw_clk, step_clk);
+       } else {
+               clk_set_parent(step_clk, pll2_pfd2_396m_clk);
+               clk_set_parent(pll1_sw_clk, step_clk);
+               if (freq_hz > clk_get_rate(pll2_pfd2_396m_clk)) {
+                       clk_set_rate(pll1_sys_clk, new_freq * 1000);
+                       clk_set_parent(pll1_sw_clk, pll1_sys_clk);
+               }
        }
 
        /* Ensure the arm clock divider is what we expect */
@@ -186,6 +210,16 @@ static int imx6q_cpufreq_probe(struct platform_device *pdev)
                goto put_clk;
        }
 
+       if (of_machine_is_compatible("fsl,imx6ul")) {
+               pll2_bus_clk = clk_get(cpu_dev, "pll2_bus");
+               secondary_sel_clk = clk_get(cpu_dev, "secondary_sel");
+               if (IS_ERR(pll2_bus_clk) || IS_ERR(secondary_sel_clk)) {
+                       dev_err(cpu_dev, "failed to get clocks specific to imx6ul\n");
+                       ret = -ENOENT;
+                       goto put_clk;
+               }
+       }
+
        arm_reg = regulator_get(cpu_dev, "arm");
        pu_reg = regulator_get_optional(cpu_dev, "pu");
        soc_reg = regulator_get(cpu_dev, "soc");
@@ -331,6 +365,10 @@ put_clk:
                clk_put(step_clk);
        if (!IS_ERR(pll2_pfd2_396m_clk))
                clk_put(pll2_pfd2_396m_clk);
+       if (!IS_ERR(pll2_bus_clk))
+               clk_put(pll2_bus_clk);
+       if (!IS_ERR(secondary_sel_clk))
+               clk_put(secondary_sel_clk);
        of_node_put(np);
        return ret;
 }
@@ -350,6 +388,8 @@ static int imx6q_cpufreq_remove(struct platform_device *pdev)
        clk_put(pll1_sw_clk);
        clk_put(step_clk);
        clk_put(pll2_pfd2_396m_clk);
+       clk_put(pll2_bus_clk);
+       clk_put(secondary_sel_clk);
 
        return 0;
 }