cpufreq: imx-cpufreq-dt: support i.MX7ULP

i.MX7ULP's ARM core clock design is totally different compared
with i.MX7D/8M SoCs which supported by imx-cpufreq-dt. It needs
get_intermediate and target_intermedate to configure clk MUX ready,
before let OPP configure ARM core clk.
                                          |---FIRC
     |------RUN---...---SCS(MUX2) --------|
ARM --(MUX1)                              |---SPLL_PFD0(CLK_SET_RATE_GATE)
     |------HSRUN--...--HSRUN_SCS(MUX3)---|
                                          |---SRIC

FIRC is step clk, SPLL_PFD0 is the normal clk driving ARM core.
MUX2 and MUX3 share same inputs. So if MUX2/MUX3 both sources from
SPLL_PFD0, both MUXes will lose input when configure SPLL_PFD0.
So the target_intermediate will configure MUX2/MUX3 to FIRC, to avoid
ARM core lose clk when configure SPLL_PFD0.
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

drivers/cpufreq/imx-cpufreq-dt.c

@@ -3,7 +3,9 @@
  * Copyright 2019 NXP
  */
 
+#include <linux/clk.h>
 #include <linux/cpu.h>
+#include <linux/cpufreq.h>
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
@@ -12,8 +14,11 @@
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/pm_opp.h>
+#include <linux/regulator/consumer.h>
 #include <linux/slab.h>
 
+#include "cpufreq-dt.h"
+
 #define OCOTP_CFG3_SPEED_GRADE_SHIFT	8
 #define OCOTP_CFG3_SPEED_GRADE_MASK	(0x3 << 8)
 #define IMX8MN_OCOTP_CFG3_SPEED_GRADE_MASK	(0xf << 8)
@@ -22,20 +27,92 @@
 #define IMX8MP_OCOTP_CFG3_MKT_SEGMENT_SHIFT    5
 #define IMX8MP_OCOTP_CFG3_MKT_SEGMENT_MASK     (0x3 << 5)
 
+#define IMX7ULP_MAX_RUN_FREQ	528000
+
 /* cpufreq-dt device registered by imx-cpufreq-dt */
 static struct platform_device *cpufreq_dt_pdev;
 static struct opp_table *cpufreq_opp_table;
+static struct device *cpu_dev;
+
+enum IMX7ULP_CPUFREQ_CLKS {
+	ARM,
+	CORE,
+	SCS_SEL,
+	HSRUN_CORE,
+	HSRUN_SCS_SEL,
+	FIRC,
+};
+
+static struct clk_bulk_data imx7ulp_clks[] = {
+	{ .id = "arm" },
+	{ .id = "core" },
+	{ .id = "scs_sel" },
+	{ .id = "hsrun_core" },
+	{ .id = "hsrun_scs_sel" },
+	{ .id = "firc" },
+};
+
+static unsigned int imx7ulp_get_intermediate(struct cpufreq_policy *policy,
+					     unsigned int index)
+{
+	return clk_get_rate(imx7ulp_clks[FIRC].clk);
+}
+
+static int imx7ulp_target_intermediate(struct cpufreq_policy *policy,
+					unsigned int index)
+{
+	unsigned int newfreq = policy->freq_table[index].frequency;
+
+	clk_set_parent(imx7ulp_clks[SCS_SEL].clk, imx7ulp_clks[FIRC].clk);
+	clk_set_parent(imx7ulp_clks[HSRUN_SCS_SEL].clk, imx7ulp_clks[FIRC].clk);
+
+	if (newfreq > IMX7ULP_MAX_RUN_FREQ)
+		clk_set_parent(imx7ulp_clks[ARM].clk,
+			       imx7ulp_clks[HSRUN_CORE].clk);
+	else
+		clk_set_parent(imx7ulp_clks[ARM].clk, imx7ulp_clks[CORE].clk);
+
+	return 0;
+}
+
+static struct cpufreq_dt_platform_data imx7ulp_data = {
+	.target_intermediate = imx7ulp_target_intermediate,
+	.get_intermediate = imx7ulp_get_intermediate,
+};
 
 static int imx_cpufreq_dt_probe(struct platform_device *pdev)
 {
-	struct device *cpu_dev = get_cpu_device(0);
+	struct platform_device *dt_pdev;
 	u32 cell_value, supported_hw[2];
 	int speed_grade, mkt_segment;
 	int ret;
 
+	cpu_dev = get_cpu_device(0);
+
 	if (!of_find_property(cpu_dev->of_node, "cpu-supply", NULL))
 		return -ENODEV;
 
+	if (of_machine_is_compatible("fsl,imx7ulp")) {
+		ret = clk_bulk_get(cpu_dev, ARRAY_SIZE(imx7ulp_clks),
+				   imx7ulp_clks);
+		if (ret)
+			return ret;
+
+		dt_pdev = platform_device_register_data(NULL, "cpufreq-dt",
+							-1, &imx7ulp_data,
+							sizeof(imx7ulp_data));
+		if (IS_ERR(dt_pdev)) {
+			clk_bulk_put(ARRAY_SIZE(imx7ulp_clks), imx7ulp_clks);
+			ret = PTR_ERR(dt_pdev);
+			dev_err(&pdev->dev, "Failed to register cpufreq-dt: %d\n", ret);
+			return ret;
+		}
+
+		cpufreq_dt_pdev = dt_pdev;
+
+		return 0;
+	}
+
 	ret = nvmem_cell_read_u32(cpu_dev, "speed_grade", &cell_value);
 	if (ret)
 		return ret;
@@ -98,7 +175,10 @@ static int imx_cpufreq_dt_probe(struct platform_device *pdev)
 static int imx_cpufreq_dt_remove(struct platform_device *pdev)
 {
 	platform_device_unregister(cpufreq_dt_pdev);
-	dev_pm_opp_put_supported_hw(cpufreq_opp_table);
+	if (!of_machine_is_compatible("fsl,imx7ulp"))
+		dev_pm_opp_put_supported_hw(cpufreq_opp_table);
+	else
+		clk_bulk_put(ARRAY_SIZE(imx7ulp_clks), imx7ulp_clks);
 
 	return 0;
 }