[src/trunk]: src/sys/arch/arm/sunxi Register a timecounter source for the 32....

[tnn <tnn%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/3ebfc653c412
branches:  trunk
changeset: 449864:3ebfc653c412
user:      tnn <tnn%NetBSD.org@localhost>
date:      Tue Mar 26 23:26:03 2019 +0000

description:
Register a timecounter source for the 32.768kHz low-power oscillator,
if it is physically present. It is preferable for timekeeping in
offline scenarios because it generally has much better long-term
frequency stability than the platform XO.

XXX: should it have higher quality rating than the 24MOSC?
I made it lower quality for now to avoid surprises for users.

diffstat:

 sys/arch/arm/sunxi/sunxi_timer.c |  41 +++++++++++++++++++++++++++++++++++++--
 1 files changed, 38 insertions(+), 3 deletions(-)

diffs (101 lines):

diff -r bcd24b3a8e02 -r 3ebfc653c412 sys/arch/arm/sunxi/sunxi_timer.c
--- a/sys/arch/arm/sunxi/sunxi_timer.c  Tue Mar 26 22:03:34 2019 +0000
+++ b/sys/arch/arm/sunxi/sunxi_timer.c  Tue Mar 26 23:26:03 2019 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: sunxi_timer.c,v 1.3 2017/12/16 20:04:38 jmcneill Exp $ */
+/* $NetBSD: sunxi_timer.c,v 1.4 2019/03/26 23:26:03 tnn Exp $ */
 
 /*-
  * Copyright (c) 2017 Jared McNeill <jmcneill%invisible.ca@localhost>
@@ -27,7 +27,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sunxi_timer.c,v 1.3 2017/12/16 20:04:38 jmcneill Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sunxi_timer.c,v 1.4 2019/03/26 23:26:03 tnn Exp $");
 
 #include <sys/param.h>
 #include <sys/kernel.h>
@@ -71,6 +71,13 @@
 #define        TMR2_INTV_VALUE_REG     0x34
 #define        TMR2_CURNT_VALUE_REG    0x38
 
+/* Timer 4 registers */
+#define        TMR4_CTRL_REG           0x50
+#define         TMR4_CTRL_RELOAD       __BIT(1)
+#define         TMR4_CTRL_EN           __BIT(0)
+#define        TMR4_INTV_VALUE_REG     0x54
+#define        TMR4_CURNT_VALUE_REG    0x58
+
 static const char * const compatible[] = {
        "allwinner,sun4i-a10-timer",
        NULL
@@ -84,6 +91,7 @@
        struct clk *sc_clk;
 
        struct timecounter sc_tc;
+       struct timecounter sc_tc_losc;
 };
 
 #define TIMER_READ(sc, reg) \
@@ -144,6 +152,14 @@
        return ~TIMER_READ(sc, TMR2_CURNT_VALUE_REG);
 }
 
+static u_int
+sunxi_timer_get_timecount_losc(struct timecounter *tc)
+{
+       struct sunxi_timer_softc * const sc = tc->tc_priv;
+
+       return ~TIMER_READ(sc, TMR4_CURNT_VALUE_REG);
+}
+
 static int
 sunxi_timer_match(device_t parent, cfdata_t cf, void *aux)
 {
@@ -158,9 +174,11 @@
        struct sunxi_timer_softc * const sc = device_private(self);
        struct fdt_attach_args * const faa = aux;
        struct timecounter *tc = &sc->sc_tc;
+       struct timecounter *tc_losc = &sc->sc_tc_losc;
        const int phandle = faa->faa_phandle;
        bus_addr_t addr;
        bus_size_t size;
+       u_int ticks;
 
        if (fdtbus_get_reg(phandle, 0, &addr, &size) != 0) {
                aprint_error(": couldn't get registers\n");
@@ -198,15 +216,32 @@
        TIMER_WRITE(sc, TMR2_CTRL_REG,
            __SHIFTIN(TMR2_CTRL_CLK_SRC_OSC24M, TMR2_CTRL_CLK_SRC) |
            TMR2_CTRL_RELOAD | TMR2_CTRL_EN);
+       /* Enable Timer 4 (timecounter for LOSC) */
+       TIMER_WRITE(sc, TMR4_INTV_VALUE_REG, ~0u);
+       TIMER_WRITE(sc, TMR4_CTRL_REG, TMR4_CTRL_RELOAD | TMR4_CTRL_EN);
 
        /* Timecounter setup */
        tc->tc_get_timecount = sunxi_timer_get_timecount;
        tc->tc_counter_mask = ~0u,
-       tc->tc_frequency = clk_get_rate(sc->sc_clk);
+       tc->tc_frequency = rate;
        tc->tc_name = "Timer 2";
        tc->tc_quality = 200;
        tc->tc_priv = sc;
        tc_init(tc);
+       tc_losc->tc_get_timecount = sunxi_timer_get_timecount_losc;
+       tc_losc->tc_counter_mask = ~0u,
+       tc_losc->tc_frequency = 32768;
+       tc_losc->tc_name = "LOSC";
+       tc_losc->tc_quality = 150;
+       tc_losc->tc_priv = sc;
+       /*
+        * LOSC is optional to implement in hardware.
+        * Make sure it ticks before registering it.
+        */
+       ticks = sunxi_timer_get_timecount_losc(tc_losc);
+       delay(100);
+       if (ticks != sunxi_timer_get_timecount_losc(tc_losc))
+               tc_init(tc_losc);
 
        /* Use this as the OS timer in UP configurations */
        if (!arm_has_mpext_p) {