* updates the conditional main_clock calculation (if AT91_MAIN_CLOCK defined) to c structure SoC access
 * add need register flags
Signed-off-by: Jens Scharsig <js_at_ng@scharsoft.de>
         */
        if (!main_clock) {
                do {
-                       tmp = at91_sys_read(AT91_CKGR_MCFR);
-               } while (!(tmp & AT91_PMC_MAINRDY));
-               main_clock = (tmp & AT91_PMC_MAINF) * (AT91_SLOW_CLOCK / 16);
+                       tmp = readl(&pmc->mcfr);
+               } while (!(tmp & AT91_PMC_MCFR_MAINRDY));
+               tmp &= AT91_PMC_MCFR_MAINF_MASK;
+               main_clock = tmp * (AT91_SLOW_CLOCK / 16);
        }
 #endif
        main_clk_rate_hz = main_clock;
 
 #define AT91_PMC_PLLBR_USBDIV_2                0x10000000
 #define AT91_PMC_PLLBR_USBDIV_4                0x20000000
 
+#define AT91_PMC_MCFR_MAINRDY          0x00010000
+#define AT91_PMC_MCFR_MAINF_MASK       0x0000FFFF
+
 #define AT91_PMC_MCKR_CSS_SLOW         0x00000000
 #define AT91_PMC_MCKR_CSS_MAIN         0x00000001
 #define AT91_PMC_MCKR_CSS_PLLA         0x00000002