mx25: add a comment documenting undocumented IPG clocks

The information in the i.MX25 Reference Manual is lacking. Add information from
the Freescale BSP.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 22 insertions, 0 deletions

diff --git a/arch/arm/mach-mx25/clock.c b/arch/arm/mach-mx25/clock.c
index 74cf27d48bfb..2bb4f1d73cbb 100644
--- a/arch/arm/mach-mx25/clock.c
+++ b/arch/arm/mach-mx25/clock.c
@@ -179,6 +179,28 @@ static void clk_cgcr_disable(struct clk *clk)
                 .secondary      = s,                    \
         }
 
+/*
+ * Note: the following IPG clock gating bits are wrongly marked "Reserved" in
+ * the i.MX25 Reference Manual Rev 1, table 15-13. The information below is
+ * taken from the Freescale released BSP.
+ *
+ * bit  reg     offset  clock
+ *
+ * 0    CGCR1   0       AUDMUX
+ * 12   CGCR1   12      ESAI
+ * 16   CGCR1   16      GPIO1
+ * 17   CGCR1   17      GPIO2
+ * 18   CGCR1   18      GPIO3
+ * 23   CGCR1   23      I2C1
+ * 24   CGCR1   24      I2C2
+ * 25   CGCR1   25      I2C3
+ * 27   CGCR1   27      IOMUXC
+ * 28   CGCR1   28      KPP
+ * 30   CGCR1   30      OWIRE
+ * 36   CGCR2   4       RTIC
+ * 51   CGCR2   19      WDOG
+ */
+
 DEFINE_CLOCK(gpt_clk,    0, CCM_CGCR0,  5, get_rate_gpt, NULL, NULL);
 DEFINE_CLOCK(uart_per_clk, 0, CCM_CGCR0, 15, get_rate_uart, NULL, NULL);
 DEFINE_CLOCK(ssi1_per_clk, 0, CCM_CGCR0, 13, get_rate_ipg, NULL, NULL);