[U-Boot-Users] [PATCH v2] PPC440EPx: Reconfigure PLL for 667MHz processor
Mike Nuss
mike at terascala.com
Wed Feb 20 17:54:20 CET 2008
On PPC440EPx without a bootstrap I2C EEPROM, the PLL can be reconfigured
after startup to change the speed of the clocks. This patch adds the
option CFG_PLL_RECONFIG. If this option is set to 667, the CPU
initialization code will reconfigure the PLL to run the system with a CPU
frequency of 667MHz and PLB frequency of 166MHz, without the need for an
external EEPROM.
Signed-off-by: Mike Nuss <mike at terascala.com>
Cc: Stefan Roese <sr at denx.de>
--
Sorry for the duplicate - updated the patch description.
Addresses changes suggested by Stefan; move PLL reconfiguration into a separate
function.
diff --git a/cpu/ppc4xx/cpu_init.c b/cpu/ppc4xx/cpu_init.c
index 2e0dd6f..fd663af 100644
--- a/cpu/ppc4xx/cpu_init.c
+++ b/cpu/ppc4xx/cpu_init.c
@@ -99,10 +99,107 @@ DECLARE_GLOBAL_DATA_PTR;
# endif
#endif /* CFG_INIT_DCACHE_CS */
+#ifndef CFG_PLL_RECONFIG
+#define CFG_PLL_RECONFIG 0
+#endif
+
+void reconfigure_pll(u32 new_cpu_freq)
+{
+#if defined(CONFIG_440EPX)
+ int reset_needed = 0;
+ u32 reg, temp;
+ u32 prbdv0, target_prbdv0, /* CLK_PRIMBD */
+ fwdva, target_fwdva, fwdvb, target_fwdvb, /* CLK_PLLD */
+ fbdv, target_fbdv, lfbdv, target_lfbdv,
+ perdv0, target_perdv0, /* CLK_PERD */
+ spcid0, target_spcid0; /* CLK_SPCID */
+
+ /* Reconfigure clocks if necessary.
+ * See PPC440EPx User's Manual, sections 8.2 and 14 */
+ if (new_cpu_freq == 667) {
+ target_prbdv0 = 2;
+ target_fwdva = 2;
+ target_fwdvb = 4;
+ target_fbdv = 20;
+ target_lfbdv = 1;
+ target_perdv0 = 4;
+ target_spcid0 = 4;
+
+ mfcpr(clk_primbd, reg);
+ temp = (reg & PRBDV_MASK) >> 24;
+ prbdv0 = temp ? temp : 8;
+ if (prbdv0 != target_prbdv0) {
+ reg &= ~PRBDV_MASK;
+ reg |= ((target_prbdv0 == 8 ? 0 : target_prbdv0) << 24);
+ mtcpr(clk_primbd, reg);
+ reset_needed = 1;
+ }
+
+ mfcpr(clk_plld, reg);
+
+ temp = (reg & PLLD_FWDVA_MASK) >> 16;
+ fwdva = temp ? temp : 16;
+
+ temp = (reg & PLLD_FWDVB_MASK) >> 8;
+ fwdvb = temp ? temp : 8;
+
+ temp = (reg & PLLD_FBDV_MASK) >> 24;
+ fbdv = temp ? temp : 32;
+
+ temp = (reg & PLLD_LFBDV_MASK);
+ lfbdv = temp ? temp : 64;
+
+ if (fwdva != target_fwdva || fbdv != target_fbdv || lfbdv != target_lfbdv) {
+ reg &= ~(PLLD_FWDVA_MASK | PLLD_FWDVB_MASK |
+ PLLD_FBDV_MASK | PLLD_LFBDV_MASK);
+ reg |= ((target_fwdva == 16 ? 0 : target_fwdva) << 16) |
+ ((target_fwdvb == 8 ? 0 : target_fwdvb) << 8) |
+ ((target_fbdv == 32 ? 0 : target_fbdv) << 24) |
+ (target_lfbdv == 64 ? 0 : target_lfbdv);
+ mtcpr(clk_plld, reg);
+ reset_needed = 1;
+ }
+
+ mfcpr(clk_perd, reg);
+ perdv0 = (reg & CPR0_PERD_PERDV0_MASK) >> 24;
+ if (perdv0 != target_perdv0) {
+ reg &= ~CPR0_PERD_PERDV0_MASK;
+ reg |= (target_perdv0 << 24);
+ mtcpr(clk_perd, reg);
+ reset_needed = 1;
+ }
+
+ mfcpr(clk_spcid, reg);
+ temp = (reg & CPR0_SPCID_SPCIDV0_MASK) >> 24;
+ spcid0 = temp ? temp : 4;
+ if (spcid0 != target_spcid0) {
+ reg &= ~CPR0_SPCID_SPCIDV0_MASK;
+ reg |= ((target_spcid0 == 4 ? 0 : target_spcid0) << 24);
+ mtcpr(clk_spcid, reg);
+ reset_needed = 1;
+ }
+
+ /* Set reload inhibit so configuration will persist across
+ * processor resets */
+ mfcpr(clk_icfg, reg);
+ reg &= ~CPR0_ICFG_RLI_MASK;
+ reg |= 1 << 31;
+ mtcpr(clk_icfg, reg);
+ }
+
+ /* Reset processor if configuration changed */
+ if (reset_needed) {
+ __asm__ __volatile__ ("sync; isync");
+ mtspr(dbcr0, 0x20000000);
+ }
+#endif
+}
+
/*
* Breath some life into the CPU...
*
- * Set up the memory map,
+ * Reconfigure PLL if necessary,
+ * set up the memory map,
* initialize a bunch of registers
*/
void
@@ -111,6 +208,7 @@ cpu_init_f (void)
#if defined(CONFIG_WATCHDOG)
unsigned long val;
#endif
+ reconfigure_pll(CFG_PLL_RECONFIG);
#if (defined(CONFIG_405EP) || defined (CONFIG_405EX)) && !defined(CFG_4xx_GPIO_TABLE)
/*
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