[resending my mail, this time with devicetree, linux-clk, and linux-arm-kernel
on cc]

On Tuesday, November 22, 2016 1:32:45 PM CET Markus Mayer wrote:

From: Markus Mayer <mmayer@broadcom.com>

This CPUfreq driver provides basic frequency scaling for older Broadcom
STB SoCs that do not use AVS firmware with DVFS support. There is no
support for voltage scaling.

Signed-off-by: Markus Mayer <mmayer@broadcom.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

This causes multiple build errors in linux-next, please fix asap or
drop the patch again. My feeling is that it's probably too late to
fix it for v4.10, but that's up to Viresh and Rafael of course.

+#define BRCMSTB_CPUFREQ_PREFIX	"brcmstb"
+#define BRCMSTB_CPUFREQ_NAME	BRCMSTB_CPUFREQ_PREFIX "-cpufreq"
+
+/* We search for these compatible strings. */
+#define BRCMSTB_DT_CPU_CLK_CTRL	"brcm,brcmstb-cpu-clk-div"
+#define BRCMSTB_DT_MEMC_DDR	"brcm,brcmstb-memc-ddr"
+#define BRCM_AVS_CPU_DATA	"brcm,avs-cpu-data-mem"
+
+/* We also need a few clocks in device tree. These are node names. */
+#define BRCMSTB_CLK_MDIV_CH0	"cpu_mdiv_ch0"
+#define BRCMSTB_CLK_NDIV_INT	"cpu_ndiv_int"
+#define BRCMSTB_CLK_SW_SCB	"sw_scb"

Not critical but the use of those macros obfuscates the DT interfaces
here and made it harder to analyse what was going on.

Also, a couple of them are lacking a DT binding.

+static int get_frequencies(const struct cpufreq_policy *policy,
+			   unsigned int *vco_freq, unsigned int *cpu_freq,
+			   unsigned int *scb_freq)
+{
+	struct clk *cpu_ndiv_int, *sw_scb;
+
+	cpu_ndiv_int = __clk_lookup(BRCMSTB_CLK_NDIV_INT);
+	if (!cpu_ndiv_int)
+		return -ENODEV;
+
+	sw_scb = __clk_lookup(BRCMSTB_CLK_SW_SCB);
+	if (!sw_scb)
+		return -ENODEV;
+
+	/* return frequencies in kHz */
+	*vco_freq = clk_get_rate(cpu_ndiv_int) / 1000;
+	*cpu_freq = clk_get_rate(policy->clk) / 1000;
+	*scb_freq = clk_get_rate(sw_scb) / 1000;
+
+	return 0;
+}

You really can't do this: 

../drivers/cpufreq/brcmstb-cpufreq.c: In function 'get_frequencies':
../drivers/cpufreq/brcmstb-cpufreq.c:71:17: error: implicit declaration of function '__clk_lookup';did you mean 'key_lookup'? [-Werror=implicit-function-declaration]
  cpu_ndiv_int = __clk_lookup(BRCMSTB_CLK_NDIV_INT);
                 ^~~~~~~~~~~~

__clk_lookup is an internal API for the clk providers.

In particular, relying on undocumented internal names of the
clk provider in a device driver is inappropriate.

+static const struct of_device_id brcmstb_cpufreq_match[] = {
+	{ .compatible = BRCMSTB_DT_CPU_CLK_CTRL },
+	{ }
+};
+MODULE_DEVICE_TABLE(platform, brcmstb_cpufreq_match);

This is a simple typo, also causing the build to fail:

    FATAL: drivers/cpufreq/brcmstb-cpufreq: sizeof(struct platform_device_id)=24 is not a modulo of the size of section __mod_platform__<identifier>_device_table=392.

	Arnd