MIPS: pistachio: Allow to enable the external timer based clocksource

This commit introduces a new config, so the user can choose to enable
the General Purpose Timer based clocksource. This option is required
to have CPUFreq support.
Signed-off-by: NEzequiel Garcia <ezequiel.garcia@imgtec.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: devicetree@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Bresticker <abrestic@chromium.org>
Cc: James Hartley <James.Hartley@imgtec.com>
Cc: Govindraj Raja <Govindraj.Raja@imgtec.com>
Cc: Damien Horsley <Damien.Horsley@imgtec.com>
Cc: James Hogan <James.Hogan@imgtec.com>
Cc: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Cc: Ezequiel Garcia <ezequiel.garcia@imgtec.com>
Patchwork: http://patchwork.linux-mips.org/patch/10887/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/Kconfig

@@ -951,6 +951,7 @@ source "arch/mips/jazz/Kconfig"
 source "arch/mips/jz4740/Kconfig"
 source "arch/mips/lantiq/Kconfig"
 source "arch/mips/lasat/Kconfig"
+source "arch/mips/pistachio/Kconfig"
 source "arch/mips/pmcs-msp71xx/Kconfig"
 source "arch/mips/ralink/Kconfig"
 source "arch/mips/sgi-ip27/Kconfig"

arch/mips/pistachio/Kconfig

+config PISTACHIO_GPTIMER_CLKSRC
+	bool "Enable General Purpose Timer based clocksource"
+	depends on MACH_PISTACHIO
+	select CLKSRC_PISTACHIO
+	select MIPS_EXTERNAL_TIMER
+	help
+	  This option enables a clocksource driver based on a Pistachio
+	  SoC General Purpose external timer.
+
+	  If you want to enable the CPUFreq, you need to enable
+	  this option.
+
+	  If you don't want to enable CPUFreq, you can leave this disabled.