Gigabeat S: Implement a genuine udelay function. Timer is gated to not run in WFI mode to save power and as such time until rollover is variable.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@19820 a1c6a512-1295-4272-9138-f99709370657

firmware/export/imx31l.h

@@ -514,6 +514,92 @@
 
 #define EPITSR_OCIF                     (1 << 0)
 
+/* GPT */
+#define GPTCR                   (*(REG32_PTR_T)(GPT1_BASE_ADDR+0x00))
+#define GPTPR                   (*(REG32_PTR_T)(GPT1_BASE_ADDR+0x04))
+#define GPTSR                   (*(REG32_PTR_T)(GPT1_BASE_ADDR+0x08))
+#define GPTIR                   (*(REG32_PTR_T)(GPT1_BASE_ADDR+0x0C))
+#define GPTOCR1                 (*(REG32_PTR_T)(GPT1_BASE_ADDR+0x10))
+#define GPTOCR2                 (*(REG32_PTR_T)(GPT1_BASE_ADDR+0x14))
+#define GPTOCR3                 (*(REG32_PTR_T)(GPT1_BASE_ADDR+0x18))
+#define GPTICR1                 (*(REG32_PTR_T)(GPT1_BASE_ADDR+0x1C))
+#define GPTICR2                 (*(REG32_PTR_T)(GPT1_BASE_ADDR+0x20))
+#define GPTCNT                  (*(REG32_PTR_T)(GPT1_BASE_ADDR+0x24))
+
+/* GPTCR */
+#define GPTCR_FO3               (0x1 << 31)
+#define GPTCR_FO2               (0x1 << 30)
+#define GPTCR_FO1               (0x1 << 29)
+
+#define GPTCR_OM3               (0x7 << 26)
+#define GPTCR_OM3_DISCONNECTED  (0x0 << 26)
+#define GPTCR_OM3_TOGGLE        (0x1 << 26)
+#define GPTCR_OM3_CLEAR         (0x2 << 26)
+#define GPTCR_OM3_SET           (0x3 << 26)
+#define GPTCR_OM3_SINGLE_COUNT  (0x4 << 26)
+    /* 0x5-0x7 same as 0x4 */
+
+#define GPTCR_OM2               (0x7 << 23)
+#define GPTCR_OM2_DISCONNECTED  (0x0 << 23)
+#define GPTCR_OM2_TOGGLE        (0x1 << 23)
+#define GPTCR_OM2_CLEAR         (0x2 << 23)
+#define GPTCR_OM2_SET           (0x3 << 23)
+#define GPTCR_OM2_SINGLE_COUNT  (0x4 << 23)
+
+    /* 0x5-0x7 same as 0x4 */
+#define GPTCR_OM1               (0x7 << 20)
+#define GPTCR_OM1_DISCONNECTED  (0x0 << 20)
+#define GPTCR_OM1_TOGGLE        (0x1 << 20)
+#define GPTCR_OM1_CLEAR         (0x2 << 20)
+#define GPTCR_OM1_SET           (0x3 << 20)
+#define GPTCR_OM1_SINGLE_COUNT  (0x4 << 20)
+
+    /* 0x5-0x7 same as 0x4 */
+#define GPTCR_IM2               (0x3 << 18)
+#define GPTCR_IM2_DISABLED      (0x0 << 18)
+#define GPTCR_IM2_RISING        (0x1 << 18)
+#define GPTCR_IM2_FALLING       (0x2 << 18)
+#define GPTCR_IM2_BOTH          (0x3 << 18)
+
+#define GPTCR_IM1               (0x3 << 16)
+#define GPTCR_IM1_DISABLED      (0x0 << 16)
+#define GPTCR_IM1_RISING        (0x1 << 16)
+#define GPTCR_IM1_FALLING       (0x2 << 16)
+#define GPTCR_IM1_BOTH          (0x3 << 16)
+
+#define GPTCR_SWR               (0x1 << 15)
+#define GPTCR_FRR               (0x1 << 9)
+
+#define GPTCR_CLKSRC            (0x7 << 6)
+#define GPTCR_CLKSRC_NONE               (0x0 << 6)
+#define GPTCR_CLKSRC_IPG_CLK            (0x1 << 6)
+#define GPTCR_CLKSRC_IPG_CLK_HIGHFREQ   (0x2 << 6)
+#define GPTCR_CLKSRC_IPG_CLK_32K        (0x4 << 6)
+/* Other values not defined */
+
+#define GPTCR_STOPEN            (0x1 << 5)
+#define GPTCR_DOZEN             (0x1 << 4)
+#define GPTCR_WAITEN            (0x1 << 3)
+#define GPTCR_DBGEN             (0x1 << 2)
+#define GPTCR_ENMODE            (0x1 << 1)
+#define GPTCR_EN                (0x1 << 0)
+
+/* GPTSR */
+#define GPTSR_ROV               (0x1 << 5)
+#define GPTSR_IF2               (0x1 << 4)
+#define GPTSR_IF1               (0x1 << 3)
+#define GPTSR_OF3               (0x1 << 2)
+#define GPTSR_OF2               (0x1 << 1)
+#define GPTSR_OF1               (0x1 << 0)
+
+/* GPTIR */
+#define GPTIR_ROV               (0x1 << 5)
+#define GPTIR_IF2IE             (0x1 << 4)
+#define GPTIR_IF1IE             (0x1 << 3)
+#define GPTIR_OF3IE             (0x1 << 2)
+#define GPTIR_OF2IE             (0x1 << 1)
+#define GPTIR_OF1IE             (0x1 << 0)
+
 /* GPIO */
 #define GPIO1_DR                (*(REG32_PTR_T)(GPIO1_BASE_ADDR+0x00))
 #define GPIO1_GDIR              (*(REG32_PTR_T)(GPIO1_BASE_ADDR+0x04))

firmware/target/arm/imx31/gigabeat-s/button-imx31.c

@@ -68,8 +68,6 @@ static __attribute__((interrupt("IRQ"))) void KPP_HANDLER(void)
 
     for (col = 0; col < 3; col++) /* Col */
     {
-        int i;
-
         /* 2. Write 1s to KPDR[10:8] setting column data to 1s */
         KPP_KPDR |= (0x7 << 8);
 
@@ -78,8 +76,7 @@ static __attribute__((interrupt("IRQ"))) void KPP_HANDLER(void)
         KPP_KPCR &= ~(0x7 << 8);
 
         /* Give the columns time to discharge */
-        for (i = 0; i < 128; i++) /* TODO: find minimum safe delay */
+        udelay(2);
-            asm volatile ("");
 
         /* 4. Configure columns as open-drain */
         KPP_KPCR |= (0x7 << 8);
@@ -94,8 +91,7 @@ static __attribute__((interrupt("IRQ"))) void KPP_HANDLER(void)
 
         /* Delay added to avoid propagating the 0 from column to row
          * when scanning. */
-        for (i = 0; i < 128; i++) /* TODO: find minimum safe delay */
+        udelay(2);
-            asm volatile ("");
 
         /* Read row input */
         button |= (~KPP_KPDR & kms[col].mask) << kms[col].shift;

firmware/target/arm/imx31/gigabeat-s/system-imx31.c

@@ -32,6 +32,8 @@
 #include "clkctl-imx31.h"
 #include "mc13783.h"
 
+/** Watchdog timer routines **/
+
 /* Initialize the watchdog timer */
 void watchdog_init(unsigned int half_seconds)
 {
@@ -57,6 +59,33 @@ void watchdog_service(void)
     WDOG_WSR = 0xaaaa;
 }
 
+/** GPT timer routines - basis for udelay **/
+
+/* Start the general-purpose timer (1MHz) */
+void gpt_start(void)
+{
+    imx31_clkctl_module_clock_gating(CG_GPT, CGM_ON_RUN_WAIT);
+    unsigned int ipg_mhz = imx31_clkctl_get_ipg_clk() / 1000000;
+
+    GPTCR &= ~GPTCR_EN; /* Disable counter */
+    GPTCR |= GPTCR_SWR; /* Reset module */
+    while (GPTCR & GPTCR_SWR);
+    /* No output
+     * No capture
+     * Enable in run mode only (doesn't tick while in WFI)
+     * Freerun mode (count to 0xFFFFFFFF and roll-over to 0x00000000)
+     */
+    GPTCR = GPTCR_FRR | GPTCR_CLKSRC_IPG_CLK;
+    GPTPR = ipg_mhz - 1;
+    GPTCR |= GPTCR_EN;
+}
+
+/* Stop the general-purpose timer */
+void gpt_stop(void)
+{
+    GPTCR &= ~GPTCR_EN;
+}
+
 int system_memory_guard(int newmode)
 {
     (void)newmode;
@@ -84,7 +113,6 @@ void system_init(void)
         /* CGR0 */
         CG_SD_MMC1,
         CG_SD_MMC2,
-        CG_GPT,
         CG_IIM,
         CG_SDMA,
         CG_CSPI3,
@@ -140,6 +168,7 @@ void system_init(void)
         imx31_clkctl_module_clock_gating(disable_clocks[i], CGM_OFF);
 
     avic_init();
+    gpt_start();
     gpio_init();
 }
 

firmware/target/arm/imx31/gigabeat-s/system-target.h

@@ -31,25 +31,18 @@
 #define CPUFREQ_MAX CPU_FREQ
 #endif
 
-/* For USB driver - no accuracy assurance */
 static inline void udelay(unsigned int usecs)
 {
-    unsigned int x;
+    unsigned stop = GPTCNT + usecs;
-    for (x = 0; x < 300*usecs; x++)
+    while (TIME_BEFORE(GPTCNT, stop));
-        asm volatile ("");
 }
 
-#if 0
-static inline void udelay(unsigned int usecs)
-{
-    volatile signed int stop = EPITCNT1 - usecs;
-    while ((signed int)EPITCNT1 > stop);
-}
-#endif
-
 void watchdog_init(unsigned int half_seconds);
 void watchdog_service(void);
 
+void gpt_start(void);
+void gpt_stop(void);
+
 /* Prepare for transition to firmware */
 void system_prepare_fw_start(void);
 void tick_stop(void);