[PATCH v8 07/10] cpufreq: dt: Add support for interconnect bandwidth scaling

[Georgi Djakov <georgi.djakov@linaro.org>]

In addition to clocks and regulators, some devices can scale the bandwidth
of their on-chip interconnect - for example between CPU and DDR memory. Add
support for that, so that platforms which support it can make use of it.

Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
---
v8:
* Picked reviewed-by tag.
* Added a separate patch to check the number of paths in DT and validate
  each one of them.

 drivers/cpufreq/Kconfig      |  1 +
 drivers/cpufreq/cpufreq-dt.c | 15 +++++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
index c3e6bd59e920..db2ad54ee67f 100644
--- a/drivers/cpufreq/Kconfig
+++ b/drivers/cpufreq/Kconfig
@@ -217,6 +217,7 @@ config CPUFREQ_DT
 
 config CPUFREQ_DT_PLATDEV
 	bool
+	depends on INTERCONNECT || !INTERCONNECT
 	help
 	  This adds a generic DT based cpufreq platdev driver for frequency
 	  management.  This creates a 'cpufreq-dt' platform device, on the
diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c
index 26fe8dfb9ce6..4ecef3257532 100644
--- a/drivers/cpufreq/cpufreq-dt.c
+++ b/drivers/cpufreq/cpufreq-dt.c
@@ -13,6 +13,7 @@
 #include <linux/cpufreq.h>
 #include <linux/cpumask.h>
 #include <linux/err.h>
+#include <linux/interconnect.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/pm_opp.h>
@@ -95,6 +96,7 @@ static int resources_available(void)
 	struct device *cpu_dev;
 	struct regulator *cpu_reg;
 	struct clk *cpu_clk;
+	struct icc_path *cpu_path;
 	int ret = 0;
 	const char *name;
 
@@ -121,6 +123,19 @@ static int resources_available(void)
 
 	clk_put(cpu_clk);
 
+	cpu_path = of_icc_get(cpu_dev, NULL);
+	ret = PTR_ERR_OR_ZERO(cpu_path);
+	if (ret) {
+		if (ret == -EPROBE_DEFER)
+			dev_dbg(cpu_dev, "defer icc path: %d\n", ret);
+		else
+			dev_err(cpu_dev, "failed to get icc path: %d\n", ret);
+
+		return ret;
+	}
+
+	icc_put(cpu_path);
+
 	name = find_supply_name(cpu_dev);
 	/* Platform doesn't require regulator */
 	if (!name)