This patch adds new at91 system clock implementation using common clk
framework.

Some peripherals need to enable a "system" clock in order to work properly.
Each system clock is given an id based on the bit position in SCER/SCDR
registers.

Signed-off-by: Boris BREZILLON <redacted>
Acked-by: Nicolas Ferre <redacted>
---
 drivers/clk/at91/Makefile     |    1 +
 drivers/clk/at91/clk-system.c |  137 +++++++++++++++++++++++++++++++++++++++++
 drivers/clk/at91/pmc.c        |    5 ++
 drivers/clk/at91/pmc.h        |    3 +
 4 files changed, 146 insertions(+)
 create mode 100644 drivers/clk/at91/clk-system.c

diff --git a/drivers/clk/at91/Makefile b/drivers/clk/at91/Makefile
index e28fb2b..c2b7068 100644
--- a/drivers/clk/at91/Makefile
+++ b/drivers/clk/at91/Makefile

@@ -4,3 +4,4 @@
 
 obj-y += pmc.o
 obj-y += clk-main.o clk-pll.o clk-plldiv.o clk-master.o
+obj-y += clk-system.o

diff --git a/drivers/clk/at91/clk-system.c b/drivers/clk/at91/clk-system.c
new file mode 100644
index 0000000..1c086f4
--- /dev/null
+++ b/drivers/clk/at91/clk-system.c

@@ -0,0 +1,137 @@
+/*
+ * drivers/clk/at91/clk-system.c