imx: add comments and remove unused struct fields

Add comment block for the imx_ddr_size function and remove the extra unused
fields from struct esd_mmdc_regs which are also not common between IMX53 and
IMX6.

Cc: Stefan Roese <sr@denx.de>
Cc: Otavio Salvador <otavio@ossystems.com.br>
Cc: Andy Ng <andreas2025@gmail.com>
Cc: Eric Nelson <eric.nelson@boundarydevices.com>
Cc: Tapani Utriainen <tapani@technexion.com>
Cc: Tom Rini <trini@ti.com>
Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Acked-by: Stefano Babic <sbabic@denx.de>
Acked-by: Nikita Kiryanov <nikita@compulab.co.il>

diff --git a/arch/arm/imx-common/cpu.c b/arch/arm/imx-common/cpu.c
index a77c4decc960eb2b08767af005d69881d58cb41f..5a09107c5ab3228441a7cd5de8aa7f375a4d3e6d 100644 (file)
--- a/arch/arm/imx-common/cpu.c
+++ b/arch/arm/imx-common/cpu.c
@@ -58,6 +58,7 @@ char *get_reset_cause(void)
 static const unsigned char col_lookup[] = {9, 10, 11, 8, 12, 9, 9, 9};
 static const unsigned char bank_lookup[] = {3, 2};
 
+/* these MMDC registers are common to the IMX53 and IMX6 */
 struct esd_mmdc_regs {
        uint32_t        ctl;
        uint32_t        pdc;
@@ -66,15 +67,6 @@ struct esd_mmdc_regs {
        uint32_t        cfg1;
        uint32_t        cfg2;
        uint32_t        misc;
-       uint32_t        scr;
-       uint32_t        ref;
-       uint32_t        rsvd1;
-       uint32_t        rsvd2;
-       uint32_t        rwd;
-       uint32_t        or;
-       uint32_t        mrr;
-       uint32_t        cfg3lp;
-       uint32_t        mr4;
 };
 
 #define ESD_MMDC_CTL_GET_ROW(mdctl)    ((ctl >> 24) & 7)
@@ -83,6 +75,12 @@ struct esd_mmdc_regs {
 #define ESD_MMDC_CTL_GET_CS1(mdctl)    ((ctl >> 30) & 1)
 #define ESD_MMDC_MISC_GET_BANK(mdmisc) ((misc >> 5) & 1)
 
+/*
+ * imx_ddr_size - return size in bytes of DRAM according MMDC config
+ * The MMDC MDCTL register holds the number of bits for row, col, and data
+ * width and the MMDC MDMISC register holds the number of banks. Combine
+ * all these bits to determine the meme size the MMDC has been configured for
+ */
 unsigned imx_ddr_size(void)
 {
        struct esd_mmdc_regs *mem = (struct esd_mmdc_regs *)MEMCTL_BASE;