From: Wolfgang Grandegger <wg@grandegger•com>
To: linuxppc-dev@ozlabs•org
Subject: [PATCH] POWERPC: MPC52xx: add function to return ext. clock frequency
Date: Thu, 15 Jan 2009 09:48:45 +0100 [thread overview]
Message-ID: <496EF86D.3010708@grandegger.com> (raw)
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>
---
arch/powerpc/include/asm/mpc52xx.h | 1
arch/powerpc/platforms/52xx/mpc52xx_common.c | 37 +++++++++++++++++++++++++++
2 files changed, 38 insertions(+)
Index: linux-2.6/arch/powerpc/include/asm/mpc52xx.h
===================================================================
--- linux-2.6.orig/arch/powerpc/include/asm/mpc52xx.h
+++ linux-2.6/arch/powerpc/include/asm/mpc52xx.h
@@ -273,6 +273,7 @@ extern void mpc5200_setup_xlb_arbiter(vo
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 */
Index: linux-2.6/arch/powerpc/platforms/52xx/mpc52xx_common.c
===================================================================
--- linux-2.6.orig/arch/powerpc/platforms/52xx/mpc52xx_common.c
+++ linux-2.6/arch/powerpc/platforms/52xx/mpc52xx_common.c
@@ -205,6 +205,43 @@ int mpc52xx_set_psc_clkdiv(int psc_id, i
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
*/
void
reply other threads:[~2009-01-15 8:48 UTC|newest]
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