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-rw-r--r--arch/arm/cpu/arm926ejs/mx28/timer.c141
1 files changed, 141 insertions, 0 deletions
diff --git a/arch/arm/cpu/arm926ejs/mx28/timer.c b/arch/arm/cpu/arm926ejs/mx28/timer.c
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+/*
+ * Freescale i.MX28 timer driver
+ *
+ * Copyright (C) 2011 Marek Vasut <marek.vasut@gmail.com>
+ * on behalf of DENX Software Engineering GmbH
+ *
+ * Based on code from LTIB:
+ * (C) Copyright 2009-2010 Freescale Semiconductor, Inc.
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+#include <asm/io.h>
+#include <asm/arch/imx-regs.h>
+#include <asm/arch/sys_proto.h>
+
+/* Maximum fixed count */
+#define TIMER_LOAD_VAL 0xffffffff
+
+DECLARE_GLOBAL_DATA_PTR;
+
+#define timestamp (gd->tbl)
+#define lastdec (gd->lastinc)
+
+/*
+ * This driver uses 1kHz clock source.
+ */
+#define MX28_INCREMENTER_HZ 1000
+
+static inline unsigned long tick_to_time(unsigned long tick)
+{
+ return tick / (MX28_INCREMENTER_HZ / CONFIG_SYS_HZ);
+}
+
+static inline unsigned long time_to_tick(unsigned long time)
+{
+ return time * (MX28_INCREMENTER_HZ / CONFIG_SYS_HZ);
+}
+
+/* Calculate how many ticks happen in "us" microseconds */
+static inline unsigned long us_to_tick(unsigned long us)
+{
+ return (us * MX28_INCREMENTER_HZ) / 1000000;
+}
+
+int timer_init(void)
+{
+ struct mx28_timrot_regs *timrot_regs =
+ (struct mx28_timrot_regs *)MXS_TIMROT_BASE;
+
+ /* Reset Timers and Rotary Encoder module */
+ mx28_reset_block(&timrot_regs->hw_timrot_rotctrl_reg);
+
+ /* Set fixed_count to 0 */
+ writel(0, &timrot_regs->hw_timrot_fixed_count0);
+
+ /* Set UPDATE bit and 1Khz frequency */
+ writel(TIMROT_TIMCTRLn_UPDATE | TIMROT_TIMCTRLn_RELOAD |
+ TIMROT_TIMCTRLn_SELECT_1KHZ_XTAL,
+ &timrot_regs->hw_timrot_timctrl0);
+
+ /* Set fixed_count to maximal value */
+ writel(TIMER_LOAD_VAL, &timrot_regs->hw_timrot_fixed_count0);
+
+ return 0;
+}
+
+ulong get_timer(ulong base)
+{
+ struct mx28_timrot_regs *timrot_regs =
+ (struct mx28_timrot_regs *)MXS_TIMROT_BASE;
+
+ /* Current tick value */
+ uint32_t now = readl(&timrot_regs->hw_timrot_running_count0);
+
+ if (lastdec >= now) {
+ /*
+ * normal mode (non roll)
+ * move stamp forward with absolut diff ticks
+ */
+ timestamp += (lastdec - now);
+ } else {
+ /* we have rollover of decrementer */
+ timestamp += (TIMER_LOAD_VAL - now) + lastdec;
+
+ }
+ lastdec = now;
+
+ return tick_to_time(timestamp) - base;
+}
+
+/* We use the HW_DIGCTL_MICROSECONDS register for sub-millisecond timer. */
+#define MX28_HW_DIGCTL_MICROSECONDS 0x8001c0c0
+
+void __udelay(unsigned long usec)
+{
+ uint32_t old, new, incr;
+ uint32_t counter = 0;
+
+ old = readl(MX28_HW_DIGCTL_MICROSECONDS);
+
+ while (counter < usec) {
+ new = readl(MX28_HW_DIGCTL_MICROSECONDS);
+
+ /* Check if the timer wrapped. */
+ if (new < old) {
+ incr = 0xffffffff - old;
+ incr += new;
+ } else {
+ incr = new - old;
+ }
+
+ /*
+ * Check if we are close to the maximum time and the counter
+ * would wrap if incremented. If that's the case, break out
+ * from the loop as the requested delay time passed.
+ */
+ if (counter + incr < counter)
+ break;
+
+ counter += incr;
+ old = new;
+ }
+}