cpufreq: dt: Don't use generic platdev driver for tango

On tango platforms, firmware configures the CPU clock, and Linux is
then only allowed to use the cpu_clk_divider to change the frequency.
Build the OPP table dynamically at init, in order to support whatever
firmware throws at us.

Signed-off-by: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

arch/arm/boot/dts/tango4-smp8758.dtsi

@@ -13,7 +13,6 @@
 			reg = <0>;
 			clocks = <&clkgen CPU_CLK>;
 			clock-latency = <1>;
-			operating-points = <1215000 0 607500 0 405000 0 243000 0 135000 0>;
 		};
 
 		cpu1: cpu@1 {

drivers/cpufreq/Kconfig.arm

@@ -241,6 +241,11 @@ config ARM_STI_CPUFREQ
 	  this config option if you wish to add CPUFreq support for STi based
 	  SoCs.
 
+config ARM_TANGO_CPUFREQ
+	bool
+	depends on CPUFREQ_DT && ARCH_TANGO
+	default y
+
 config ARM_TEGRA20_CPUFREQ
 	bool "Tegra20 CPUFreq support"
 	depends on ARCH_TEGRA

drivers/cpufreq/Makefile

@@ -75,6 +75,7 @@ obj-$(CONFIG_ARM_SA1110_CPUFREQ)	+= sa1110-cpufreq.o
 obj-$(CONFIG_ARM_SCPI_CPUFREQ)		+= scpi-cpufreq.o
 obj-$(CONFIG_ARM_SPEAR_CPUFREQ)		+= spear-cpufreq.o
 obj-$(CONFIG_ARM_STI_CPUFREQ)		+= sti-cpufreq.o
+obj-$(CONFIG_ARM_TANGO_CPUFREQ)		+= tango-cpufreq.o
 obj-$(CONFIG_ARM_TEGRA20_CPUFREQ)	+= tegra20-cpufreq.o
 obj-$(CONFIG_ARM_TEGRA124_CPUFREQ)	+= tegra124-cpufreq.o
 obj-$(CONFIG_ARM_TEGRA186_CPUFREQ)	+= tegra186-cpufreq.o

drivers/cpufreq/cpufreq-dt-platdev.c

@@ -80,8 +80,6 @@ static const struct of_device_id machines[] __initconst = {
 	{ .compatible = "rockchip,rk3368", },
 	{ .compatible = "rockchip,rk3399", },
 
-	{ .compatible = "sigma,tango4" },
-
 	{ .compatible = "socionext,uniphier-pro5", },
 	{ .compatible = "socionext,uniphier-pxs2", },
 	{ .compatible = "socionext,uniphier-ld6b", },

drivers/cpufreq/tango-cpufreq.c

@@ -0,0 +1,38 @@
+#include <linux/of.h>
+#include <linux/cpu.h>
+#include <linux/clk.h>
+#include <linux/pm_opp.h>
+#include <linux/platform_device.h>
+
+static const struct of_device_id machines[] __initconst = {
+	{ .compatible = "sigma,tango4" },
+	{ /* sentinel */ }
+};
+
+static int __init tango_cpufreq_init(void)
+{
+	struct device *cpu_dev = get_cpu_device(0);
+	unsigned long max_freq;
+	struct clk *cpu_clk;
+	void *res;
+
+	if (!of_match_node(machines, of_root))
+		return -ENODEV;
+
+	cpu_clk = clk_get(cpu_dev, NULL);
+	if (IS_ERR(cpu_clk))
+		return -ENODEV;
+
+	max_freq = clk_get_rate(cpu_clk);
+
+	dev_pm_opp_add(cpu_dev, max_freq / 1, 0);
+	dev_pm_opp_add(cpu_dev, max_freq / 2, 0);
+	dev_pm_opp_add(cpu_dev, max_freq / 3, 0);
+	dev_pm_opp_add(cpu_dev, max_freq / 5, 0);
+	dev_pm_opp_add(cpu_dev, max_freq / 9, 0);
+
+	res = platform_device_register_data(NULL, "cpufreq-dt", -1, NULL, 0);
+
+	return PTR_ERR_OR_ZERO(res);
+}
+device_initcall(tango_cpufreq_init);