powerpc/5200: add function to return external clock frequency

This patch adds the utility function mpc52xx_get_xtal_freq() to get
the frequency of the external oscillator clock connected to the pin
SYS_XTAL_IN. The MSCAN may us it as clock source. Unfortunately, this
value is not available from the FDT blob, but it can be determined
from the IPB frequency.

Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

diff --git a/arch/powerpc/include/asm/mpc52xx.h b/arch/powerpc/include/asm/mpc52xx.h
index 81a23932a160c7e47aaa4ceb359e591ee7ee5c6f..52e049cd9e687c09b2b95eb5b71082cecca5bfb9 100644 (file)
--- a/arch/powerpc/include/asm/mpc52xx.h
+++ b/arch/powerpc/include/asm/mpc52xx.h
@@ -273,6 +273,7 @@ extern void mpc5200_setup_xlb_arbiter(void);
 extern void mpc52xx_declare_of_platform_devices(void);
 extern void mpc52xx_map_common_devices(void);
 extern int mpc52xx_set_psc_clkdiv(int psc_id, int clkdiv);
+extern unsigned int mpc52xx_get_xtal_freq(struct device_node *node);
 extern void mpc52xx_restart(char *cmd);
 
 /* mpc52xx_pic.c */

diff --git a/arch/powerpc/platforms/52xx/mpc52xx_common.c b/arch/powerpc/platforms/52xx/mpc52xx_common.c
index e9d2cf632eebbf2da2b06d06bb06e5c31cf7b3e0..8e3dd5a0f228d67fc305731ebddf12fbe2f80b39 100644 (file)
--- a/arch/powerpc/platforms/52xx/mpc52xx_common.c
+++ b/arch/powerpc/platforms/52xx/mpc52xx_common.c
@@ -205,6 +205,43 @@ int mpc52xx_set_psc_clkdiv(int psc_id, int clkdiv)
 }
 EXPORT_SYMBOL(mpc52xx_set_psc_clkdiv);
 
+/**
+ * mpc52xx_get_xtal_freq - Get SYS_XTAL_IN frequency for a device
+ *
+ * @node: device node
+ *
+ * Returns the frequency of the external oscillator clock connected
+ * to the SYS_XTAL_IN pin, or 0 if it cannot be determined.
+ */
+unsigned int mpc52xx_get_xtal_freq(struct device_node *node)
+{
+       u32 val;
+       unsigned int freq;
+
+       if (!mpc52xx_cdm)
+               return 0;
+
+       freq = mpc52xx_find_ipb_freq(node);
+       if (!freq)
+               return 0;
+
+       if (in_8(&mpc52xx_cdm->ipb_clk_sel) & 0x1)
+               freq *= 2;
+
+       val  = in_be32(&mpc52xx_cdm->rstcfg);
+       if (val & (1 << 5))
+               freq *= 8;
+       else
+               freq *= 4;
+       if (val & (1 << 6))
+               freq /= 12;
+       else
+               freq /= 16;
+
+       return freq;
+}
+EXPORT_SYMBOL(mpc52xx_get_xtal_freq);
+
 /**
  * mpc52xx_restart: ppc_md->restart hook for mpc5200 using the watchdog timer
  */