Merge pull request #50 from sifive/common_plic

FE-203 Move plic_driver code to a common location.

8 files changed, 347 insertions, 6 deletions

diff --git a/bsp/drivers/fe300prci/fe300prci_driver.c b/bsp/drivers/fe300prci/fe300prci_driver.c
new file mode 100644
index 0000000..2d9c52f
--- /dev/null
+++ b/bsp/drivers/fe300prci/fe300prci_driver.c
@@ -0,0 +1,252 @@
+// See LICENSE file for license details
+
+#include "platform.h"
+
+#ifdef PRCI_BASE_ADDR
+#include "fe300prci/fe300prci_driver.h"
+#include <unistd.h>
+
+#define rdmcycle(x)  {				       \
+    uint32_t lo, hi, hi2;			       \
+    __asm__ __volatile__ ("1:\n\t"		       \
+			  "csrr %0, mcycleh\n\t"       \
+			  "csrr %1, mcycle\n\t"	       \
+			  "csrr %2, mcycleh\n\t"		\
+			  "bne  %0, %2, 1b\n\t"			\
+			  : "=r" (hi), "=r" (lo), "=r" (hi2)) ;	\
+    *(x) = lo | ((uint64_t) hi << 32); 				\
+  }
+
+uint32_t PRCI_measure_mcycle_freq(uint32_t mtime_ticks, uint32_t mtime_freq)
+{
+
+  uint32_t start_mtime = CLINT_REG(CLINT_MTIME);
+  uint32_t end_mtime = start_mtime + mtime_ticks + 1;
+
+  // Make sure we won't get rollover.
+  while (end_mtime < start_mtime){
+    start_mtime = CLINT_REG(CLINT_MTIME);
+    end_mtime = start_mtime + mtime_ticks + 1;
+  }
+
+  // Don't start measuring until mtime edge.
+  uint32_t tmp = start_mtime;
+  do {
+    start_mtime = CLINT_REG(CLINT_MTIME);
+  } while (start_mtime == tmp);
+  
+  uint64_t start_mcycle;
+  rdmcycle(&start_mcycle);
+  
+  while (CLINT_REG(CLINT_MTIME) < end_mtime) ;
+  
+  uint64_t end_mcycle;
+  rdmcycle(&end_mcycle);
+  uint32_t difference = (uint32_t) (end_mcycle - start_mcycle);
+
+  uint64_t freq = ((uint64_t) difference * mtime_freq) / mtime_ticks;
+  return (uint32_t) freq & 0xFFFFFFFF;
+  
+}
+ 
+
+void PRCI_use_hfrosc(int div, int trim)
+{
+  // Make sure the HFROSC is running at its default setting
+  // It is OK to change this even if we are running off of it.
+  
+  PRCI_REG(PRCI_HFROSCCFG) = (ROSC_DIV(div) | ROSC_TRIM(trim) | ROSC_EN(1));
+
+  while ((PRCI_REG(PRCI_HFROSCCFG) & ROSC_RDY(1)) == 0);
+  
+  PRCI_REG(PRCI_PLLCFG) &= ~PLL_SEL(1);
+}
+
+void PRCI_use_pll(int refsel, int bypass,
+			 int r, int f, int q, int finaldiv,
+			 int hfroscdiv, int hfrosctrim)
+{
+  // Ensure that we aren't running off the PLL before we mess with it.
+  if (PRCI_REG(PRCI_PLLCFG) & PLL_SEL(1)) {
+    // Make sure the HFROSC is running at its default setting
+    PRCI_use_hfrosc(4, 16);
+  }
+  
+  // Set PLL Source to be HFXOSC if desired.
+  uint32_t config_value = 0;
+
+  config_value |= PLL_REFSEL(refsel);
+  
+  if (bypass) {
+    // Bypass
+    config_value |= PLL_BYPASS(1);
+
+    PRCI_REG(PRCI_PLLCFG) = config_value;
+
+    // If we don't have an HFXTAL, this doesn't really matter.
+    // Set our Final output divide to divide-by-1:
+    PRCI_REG(PRCI_PLLDIV) = (PLL_FINAL_DIV_BY_1(1) | PLL_FINAL_DIV(0));
+  } else {
+  
+    // To overclock, use the hfrosc
+    if (hfrosctrim >= 0 && hfroscdiv >= 0) {
+      PRCI_use_hfrosc(hfroscdiv, hfrosctrim);
+    }
+    
+    // Set DIV Settings for PLL
+    
+    // (Legal values of f_REF are 6-48MHz)
+
+    // Set DIVR to divide-by-2 to get 8MHz frequency
+    // (legal values of f_R are 6-12 MHz)
+
+    config_value |= PLL_BYPASS(1);
+    config_value |= PLL_R(r);
+
+    // Set DIVF to get 512Mhz frequncy
+    // There is an implied multiply-by-2, 16Mhz.
+    // So need to write 32-1
+    // (legal values of f_F are 384-768 MHz)
+    config_value |= PLL_F(f);
+
+    // Set DIVQ to divide-by-2 to get 256 MHz frequency
+    // (legal values of f_Q are 50-400Mhz)
+    config_value |= PLL_Q(q);
+
+    // Set our Final output divide to divide-by-1:
+    if (finaldiv == 1){
+      PRCI_REG(PRCI_PLLDIV) = (PLL_FINAL_DIV_BY_1(1) | PLL_FINAL_DIV(0));
+    } else {
+      PRCI_REG(PRCI_PLLDIV) = (PLL_FINAL_DIV(finaldiv-1));
+    }
+
+    PRCI_REG(PRCI_PLLCFG) = config_value;
+
+    // Un-Bypass the PLL.
+    PRCI_REG(PRCI_PLLCFG) &= ~PLL_BYPASS(1);
+
+    // Wait for PLL Lock
+    // Note that the Lock signal can be glitchy.
+    // Need to wait 100 us
+    // RTC is running at 32kHz.
+    // So wait 4 ticks of RTC.
+    uint32_t now = CLINT_REG(CLINT_MTIME);
+    while (CLINT_REG(CLINT_MTIME) - now < 4) ;
+    
+    // Now it is safe to check for PLL Lock
+    while ((PRCI_REG(PRCI_PLLCFG) & PLL_LOCK(1)) == 0);
+
+  }
+
+  // Switch over to PLL Clock source
+  PRCI_REG(PRCI_PLLCFG) |= PLL_SEL(1);
+
+  // If we're running off HFXOSC, turn off the HFROSC to
+  // save power.
+  if (refsel) {
+    PRCI_REG(PRCI_HFROSCCFG) &= ~ROSC_EN(1);
+  }
+  
+}
+
+void PRCI_use_default_clocks()
+{
+  // Turn off the LFROSC
+  AON_REG(AON_LFROSC) &= ~ROSC_EN(1);
+
+  // Use HFROSC
+  PRCI_use_hfrosc(4, 16);
+}
+
+void PRCI_use_hfxosc(uint32_t finaldiv)
+{
+  
+  PRCI_use_pll(1, // Use HFXTAL
+	       1, // Bypass = 1
+	       0, // PLL settings don't matter
+	       0, // PLL settings don't matter
+	       0, // PLL settings don't matter
+	       finaldiv,
+	       -1,
+	       -1);
+}
+
+// This is a generic function, which
+// doesn't span the entire range of HFROSC settings.
+// It only adjusts the trim, which can span a hundred MHz or so.
+// This function does not check the legality of the PLL settings
+// at all, and it is quite possible to configure invalid PLL settings
+// this way.
+// It returns the actual measured CPU frequency.
+
+uint32_t PRCI_set_hfrosctrim_for_f_cpu(uint32_t f_cpu, PRCI_freq_target target )
+{
+
+  uint32_t hfrosctrim = 0;
+  uint32_t hfroscdiv = 4;
+  uint32_t prev_trim = 0;
+
+  // In this function we use PLL settings which
+  // will give us a 32x multiplier from the output
+  // of the HFROSC source to the output of the
+  // PLL. We first measure our HFROSC to get the
+  // right trim, then finally use it as the PLL source.
+  // We should really check here that the f_cpu
+  // requested is something in the limit of the PLL. For
+  // now that is up to the user.
+
+  // This will undershoot for frequencies not divisible by 16.
+  uint32_t desired_hfrosc_freq = (f_cpu/ 16);
+
+  PRCI_use_hfrosc(hfroscdiv, hfrosctrim);
+  
+  // Ignore the first run (for icache reasons)
+  uint32_t cpu_freq = PRCI_measure_mcycle_freq(3000, RTC_FREQ);
+
+  cpu_freq = PRCI_measure_mcycle_freq(3000, RTC_FREQ);
+  uint32_t prev_freq = cpu_freq;
+  
+  while ((cpu_freq < desired_hfrosc_freq) && (hfrosctrim < 0x1F)){
+    prev_trim = hfrosctrim;
+    prev_freq = cpu_freq;
+    hfrosctrim ++;
+    PRCI_use_hfrosc(hfroscdiv, hfrosctrim);
+    cpu_freq = PRCI_measure_mcycle_freq(3000, RTC_FREQ);
+  } 
+
+  // We couldn't go low enough
+  if (prev_freq > desired_hfrosc_freq){
+    PRCI_use_pll(0, 0, 1, 31, 1, 1, hfroscdiv, prev_trim);
+    cpu_freq = PRCI_measure_mcycle_freq(1000, RTC_FREQ);
+    return cpu_freq;
+  }
+  
+  // We couldn't go high enough
+  if (cpu_freq < desired_hfrosc_freq){
+    PRCI_use_pll(0, 0, 1, 31, 1, 1, hfroscdiv, prev_trim);
+    cpu_freq = PRCI_measure_mcycle_freq(1000, RTC_FREQ);
+    return cpu_freq;
+  }
+
+  // Check for over/undershoot
+  switch(target) {
+  case(PRCI_FREQ_CLOSEST):
+    if ((desired_hfrosc_freq - prev_freq) < (cpu_freq - desired_hfrosc_freq)) {
+      PRCI_use_pll(0, 0, 1, 31, 1, 1, hfroscdiv, prev_trim);
+    } else {
+      PRCI_use_pll(0, 0, 1, 31, 1, 1, hfroscdiv, hfrosctrim);
+    }
+    break;
+  case(PRCI_FREQ_UNDERSHOOT):
+    PRCI_use_pll(0, 0, 1, 31, 1, 1, hfroscdiv, prev_trim);
+    break;
+  default:
+    PRCI_use_pll(0, 0, 1, 31, 1, 1, hfroscdiv, hfrosctrim);
+  }
+
+  cpu_freq =  PRCI_measure_mcycle_freq(1000, RTC_FREQ);
+  return cpu_freq;
+
+}
+
+#endif
diff --git a/bsp/drivers/fe300prci/fe300prci_driver.h b/bsp/drivers/fe300prci/fe300prci_driver.h
new file mode 100644
index 0000000..7100f46
--- /dev/null
+++ b/bsp/drivers/fe300prci/fe300prci_driver.h
@@ -0,0 +1,79 @@
+// See LICENSE file for license details
+
+#ifndef _FE300PRCI_DRIVER_H_
+#define _FE300PRCI_DRIVER_H_
+
+__BEGIN_DECLS
+
+#include <unistd.h>
+
+typedef enum prci_freq_target {
+  
+  PRCI_FREQ_OVERSHOOT,
+  PRCI_FREQ_CLOSEST,
+  PRCI_FREQ_UNDERSHOOT
+
+} PRCI_freq_target;
+
+/* Measure and return the approximate frequency of the 
+ * CPU, as given by measuring the mcycle counter against 
+ * the mtime ticks.
+ */
+uint32_t PRCI_measure_mcycle_freq(uint32_t mtime_ticks, uint32_t mtime_freq);
+
+/* Safely switch over to the HFROSC using the given div
+ * and trim settings.
+ */
+void PRCI_use_hfrosc(int div, int trim);
+
+/* Safely switch over to the 16MHz HFXOSC,
+ * applying the finaldiv clock divider (1 is the lowest
+ * legal value).
+ */
+void PRCI_use_hfxosc(uint32_t finaldiv);
+
+/* Safely switch over to the PLL using the given
+ * settings.
+ * 
+ * Note that not all combinations of the inputs are actually
+ * legal, and this function does not check for their
+ * legality ("safely" means that this function won't turn off
+ * or glitch the clock the CPU is actually running off, but
+ * doesn't protect against you making it too fast or slow.)
+ */
+
+void PRCI_use_pll(int refsel, int bypass,
+			 int r, int f, int q, int finaldiv,
+			 int hfroscdiv, int hfrosctrim);
+
+/* Use the default clocks configured at reset.
+ * This is ~16Mhz HFROSC and turns off the LFROSC
+ * (on the current FE310 Dev Platforms, an external LFROSC is 
+ * used as it is more power efficient).
+ */
+void PRCI_use_default_clocks();
+
+/* This routine will adjust the HFROSC trim
+ * while using HFROSC as the clock source, 
+ * measure the resulting frequency, then
+ * use it as the PLL clock source, 
+ * in an attempt to get over, under, or close to the 
+ * requested frequency. It returns the actual measured 
+ * frequency. 
+ *
+ * Note that the requested frequency must be within the 
+ * range supported by the PLL so not all values are 
+ * achievable with this function, and not all 
+ * are guaranteed to actually work. The PLL
+ * is rated higher than the hardware.
+ * 
+ * There is no check on the desired f_cpu frequency, it
+ * is up to the user to specify something reasonable.
+ */
+
+uint32_t PRCI_set_hfrosctrim_for_f_cpu(uint32_t f_cpu, PRCI_freq_target target);
+
+__END_DECLS
+
+#endif
+  
diff --git a/software/demo_gpio/plic_driver.c b/bsp/drivers/plic/plic_driver.c
index 01b7e6e..b27d7a5 100644
--- a/software/demo_gpio/plic_driver.c
+++ b/bsp/drivers/plic/plic_driver.c
@@ -1,7 +1,7 @@
 // See LICENSE for license details.
 
 #include "sifive/devices/plic.h"
-#include "plic_driver.h"
+#include "plic/plic_driver.h"
 #include "platform.h"
 #include "encoding.h"
 #include <string.h>
diff --git a/software/demo_gpio/plic_driver.h b/bsp/drivers/plic/plic_driver.h
index 66410be..e7d609b 100644
--- a/software/demo_gpio/plic_driver.h
+++ b/bsp/drivers/plic/plic_driver.h
@@ -3,6 +3,9 @@
 #ifndef PLIC_DRIVER_H
 #define PLIC_DRIVER_H
 
+
+__BEGIN_DECLS
+
 #include "platform.h"
 
 typedef struct __plic_instance_t
@@ -42,5 +45,7 @@ plic_source PLIC_claim_interrupt(plic_instance_t * this_plic);
 
 void PLIC_complete_interrupt(plic_instance_t * this_plic,
 			     plic_source source);
-  
+
+__END_DECLS
+
 #endif
diff --git a/bsp/env/common.mk b/bsp/env/common.mk
index 420c196..74f5582 100644
--- a/bsp/env/common.mk
+++ b/bsp/env/common.mk
@@ -19,6 +19,7 @@ C_SRCS += $(PLATFORM_DIR)/init.c
 LINKER_SCRIPT := $(PLATFORM_DIR)/link.lds
 
 INCLUDES += -I$(BSP_BASE)/include
+INCLUDES += -I$(BSP_BASE)/drivers/
 INCLUDES += -I$(ENV_DIR)
 INCLUDES += -I$(PLATFORM_DIR)
 
@@ -47,7 +48,7 @@ $(ASM_OBJS): %.o: %.S $(HEADERS)
 	$(CC) $(CFLAGS) $(INCLUDES) -c -o $@ $<
 
 $(C_OBJS): %.o: %.c $(HEADERS)
-	$(CC) $(CFLAGS) $(INCLUDES) -c -o $@ $<
+	$(CC) $(CFLAGS) $(INCLUDES) -include sys/cdefs.h -c -o $@ $<
 
 .PHONY: clean
 clean:
diff --git a/bsp/env/hifive1.h b/bsp/env/hifive1.h
index 11b98f8..4c65f18 100644
--- a/bsp/env/hifive1.h
+++ b/bsp/env/hifive1.h
@@ -74,6 +74,8 @@
 #define HAS_HFXOSC 1
 #define HAS_LFROSC_BYPASS 1
 
+#define RTC_FREQ 32768
+
 void write_hex(int fd, uint32_t hex);
 
 #endif /* _SIFIVE_HIFIVE1_H */
diff --git a/software/demo_gpio/Makefile b/software/demo_gpio/Makefile
index 04a11b7..b181c5f 100644
--- a/software/demo_gpio/Makefile
+++ b/software/demo_gpio/Makefile
@@ -1,7 +1,9 @@
 TARGET = demo_gpio
-C_SRCS += demo_gpio.c
-C_SRCS += plic_driver.c
 CFLAGS += -O2 -fno-builtin-printf -DUSE_PLIC -DUSE_M_TIME
 
 BSP_BASE = ../../bsp
+
+C_SRCS += demo_gpio.c
+C_SRCS += $(BSP_BASE)/drivers/plic/plic_driver.c
+
 include $(BSP_BASE)/env/common.mk
diff --git a/software/demo_gpio/demo_gpio.c b/software/demo_gpio/demo_gpio.c
index 00bc8cd..bfa388e 100644
--- a/software/demo_gpio/demo_gpio.c
+++ b/software/demo_gpio/demo_gpio.c
@@ -4,7 +4,7 @@
 #include <stdlib.h>
 #include "platform.h"
 #include <string.h>
-#include "plic_driver.h"
+#include "plic/plic_driver.h"
 #include "encoding.h"
 #include <unistd.h>
 #include "stdatomic.h"