SPDX: Convert all of our single license tags to Linux Kernel style

[oweals/u-boot.git] / drivers / timer / tsc_timer.c

diff --git a/drivers/timer/tsc_timer.c b/drivers/timer/tsc_timer.c
index 4d01c9bce793231a7e1d9531936800fb22d7d383..c7fefd20319fcf1c0972c92ee92effdc100ff45d 100644 (file)
--- a/drivers/timer/tsc_timer.c
+++ b/drivers/timer/tsc_timer.c
@@ -1,10 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0+
 /*
  * Copyright (c) 2012 The Chromium OS Authors.
  *
  * TSC calibration codes are adapted from Linux kernel
  * arch/x86/kernel/tsc_msr.c and arch/x86/kernel/tsc.c
- *
- * SPDX-License-Identifier:    GPL-2.0+
  */
 
 #include <common.h>
@@ -18,13 +17,7 @@
 #include <asm/msr.h>
 #include <asm/u-boot-x86.h>
 
-/* CPU reference clock frequency: in KHz */
-#define FREQ_83                83200
-#define FREQ_100       99840
-#define FREQ_133       133200
-#define FREQ_166       166400
-
-#define MAX_NUM_FREQS  8
+#define MAX_NUM_FREQS  9
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -46,17 +39,20 @@ struct freq_desc {
 
 static struct freq_desc freq_desc_tables[] = {
        /* PNW */
-       { 6, 0x27, 0, { 0, 0, 0, 0, 0, FREQ_100, 0, FREQ_83 } },
+       { 6, 0x27, 0, { 0, 0, 0, 0, 0, 99840, 0, 83200, 0 } },
        /* CLV+ */
-       { 6, 0x35, 0, { 0, FREQ_133, 0, 0, 0, FREQ_100, 0, FREQ_83 } },
-       /* TNG */
-       { 6, 0x4a, 1, { 0, FREQ_100, FREQ_133, 0, 0, 0, 0, 0 } },
-       /* VLV2 */
-       { 6, 0x37, 1, { FREQ_83, FREQ_100, FREQ_133, FREQ_166, 0, 0, 0, 0 } },
+       { 6, 0x35, 0, { 0, 133200, 0, 0, 0, 99840, 0, 83200, 0 } },
+       /* TNG - Intel Atom processor Z3400 series */
+       { 6, 0x4a, 1, { 0, 100000, 133300, 0, 0, 0, 0, 0, 0 } },
+       /* VLV2 - Intel Atom processor E3000, Z3600, Z3700 series */
+       { 6, 0x37, 1, { 83300, 100000, 133300, 116700, 80000, 0, 0, 0, 0 } },
+       /* ANN - Intel Atom processor Z3500 series */
+       { 6, 0x5a, 1, { 83300, 100000, 133300, 100000, 0, 0, 0, 0, 0 } },
+       /* AMT - Intel Atom processor X7-Z8000 and X5-Z8000 series */
+       { 6, 0x4c, 1, { 83300, 100000, 133300, 116700,
+                       80000, 93300, 90000, 88900, 87500 } },
        /* Ivybridge */
-       { 6, 0x3a, 2, { 0, 0, 0, 0, 0, 0, 0, 0 } },
-       /* ANN */
-       { 6, 0x5a, 1, { FREQ_83, FREQ_100, FREQ_133, FREQ_100, 0, 0, 0, 0 } },
+       { 6, 0x3a, 2, { 0, 0, 0, 0, 0, 0, 0, 0, 0 } },
 };
 
 static int match_cpu(u8 family, u8 model)
@@ -77,11 +73,16 @@ static int match_cpu(u8 family, u8 model)
        (freq_desc_tables[cpu_index].freqs[freq_id])
 
 /*
- * Do MSR calibration only for known/supported CPUs.
+ * TSC on Intel Atom SoCs capable of determining TSC frequency by MSR is
+ * reliable and the frequency is known (provided by HW).
+ *
+ * On these platforms PIT/HPET is generally not available so calibration won't
+ * work at all and there is no other clocksource to act as a watchdog for the
+ * TSC, so we have no other choice than to trust it.
  *
- * Returns the calibration value or 0 if MSR calibration failed.
+ * Returns the TSC frequency in MHz or 0 if HW does not provide it.
  */
-static unsigned long __maybe_unused try_msr_calibrate_tsc(void)
+static unsigned long __maybe_unused cpu_mhz_from_msr(void)
 {
        u32 lo, hi, ratio, freq_id, freq;
        unsigned long res;
@@ -103,12 +104,9 @@ static unsigned long __maybe_unused try_msr_calibrate_tsc(void)
        }
        debug("Maximum core-clock to bus-clock ratio: 0x%x\n", ratio);
 
-       if (!ratio)
-               goto fail;
-
        if (freq_desc_tables[cpu_index].msr_plat == 2) {
                /* TODO: Figure out how best to deal with this */
-               freq = FREQ_100;
+               freq = 100000;
                debug("Using frequency: %u KHz\n", freq);
        } else {
                /* Get FSB FREQ ID */
@@ -118,18 +116,12 @@ static unsigned long __maybe_unused try_msr_calibrate_tsc(void)
                debug("Resolved frequency ID: %u, frequency: %u KHz\n",
                      freq_id, freq);
        }
-       if (!freq)
-               goto fail;
 
        /* TSC frequency = maximum resolved freq * maximum resolved bus ratio */
        res = freq * ratio / 1000;
        debug("TSC runs at %lu MHz\n", res);
 
        return res;
-
-fail:
-       debug("Fast TSC calibration using MSR failed\n");
-       return 0;
 }
 
 /*
@@ -338,32 +330,52 @@ static int tsc_timer_get_count(struct udevice *dev, u64 *count)
        return 0;
 }
 
-static int tsc_timer_probe(struct udevice *dev)
+static void tsc_timer_ensure_setup(void)
 {
-       struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
-
+       if (gd->arch.tsc_base)
+               return;
        gd->arch.tsc_base = rdtsc();
 
        /*
         * If there is no clock frequency specified in the device tree,
         * calibrate it by ourselves.
         */
-       if (!uc_priv->clock_rate) {
+       if (!gd->arch.clock_rate) {
                unsigned long fast_calibrate;
 
-               fast_calibrate = try_msr_calibrate_tsc();
+               fast_calibrate = cpu_mhz_from_msr();
                if (!fast_calibrate) {
                        fast_calibrate = quick_pit_calibrate();
                        if (!fast_calibrate)
                                panic("TSC frequency is ZERO");
                }
 
-               uc_priv->clock_rate = fast_calibrate * 1000000;
+               gd->arch.clock_rate = fast_calibrate * 1000000;
        }
+}
+
+static int tsc_timer_probe(struct udevice *dev)
+{
+       struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+
+       tsc_timer_ensure_setup();
+       uc_priv->clock_rate = gd->arch.clock_rate;
 
        return 0;
 }
 
+unsigned long notrace timer_early_get_rate(void)
+{
+       tsc_timer_ensure_setup();
+
+       return gd->arch.clock_rate;
+}
+
+u64 notrace timer_early_get_count(void)
+{
+       return rdtsc() - gd->arch.tsc_base;
+}
+
 static const struct timer_ops tsc_timer_ops = {
        .get_count = tsc_timer_get_count,
 };