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Diffstat (limited to 'arch/mips/kernel/csrc-powertv.c')
-rw-r--r--arch/mips/kernel/csrc-powertv.c180
1 files changed, 180 insertions, 0 deletions
diff --git a/arch/mips/kernel/csrc-powertv.c b/arch/mips/kernel/csrc-powertv.c
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index 000000000000..a27c16c8690e
--- /dev/null
+++ b/arch/mips/kernel/csrc-powertv.c
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+/*
+ * Copyright (C) 2008 Scientific-Atlanta, Inc.
+ *
+ * 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.
+ */
+/*
+ * The file comes from kernel/csrc-r4k.c
+ */
+#include <linux/clocksource.h>
+#include <linux/init.h>
+
+#include <asm/time.h> /* Not included in linux/time.h */
+
+#include <asm/mach-powertv/asic_regs.h>
+#include "powertv-clock.h"
+
+/* MIPS PLL Register Definitions */
+#define PLL_GET_M(x) (((x) >> 8) & 0x000000FF)
+#define PLL_GET_N(x) (((x) >> 16) & 0x000000FF)
+#define PLL_GET_P(x) (((x) >> 24) & 0x00000007)
+
+/*
+ * returns: Clock frequency in kHz
+ */
+unsigned int __init mips_get_pll_freq(void)
+{
+ unsigned int pll_reg, m, n, p;
+ unsigned int fin = 54000; /* Base frequency in kHz */
+ unsigned int fout;
+
+ /* Read PLL register setting */
+ pll_reg = asic_read(mips_pll_setup);
+ m = PLL_GET_M(pll_reg);
+ n = PLL_GET_N(pll_reg);
+ p = PLL_GET_P(pll_reg);
+ pr_info("MIPS PLL Register:0x%x M=%d N=%d P=%d\n", pll_reg, m, n, p);
+
+ /* Calculate clock frequency = (2 * N * 54MHz) / (M * (2**P)) */
+ fout = ((2 * n * fin) / (m * (0x01 << p)));
+
+ pr_info("MIPS Clock Freq=%d kHz\n", fout);
+
+ return fout;
+}
+
+static cycle_t c0_hpt_read(struct clocksource *cs)
+{
+ return read_c0_count();
+}
+
+static struct clocksource clocksource_mips = {
+ .name = "powertv-counter",
+ .read = c0_hpt_read,
+ .mask = CLOCKSOURCE_MASK(32),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static void __init powertv_c0_hpt_clocksource_init(void)
+{
+ unsigned int pll_freq = mips_get_pll_freq();
+
+ pr_info("CPU frequency %d.%02d MHz\n", pll_freq / 1000,
+ (pll_freq % 1000) * 100 / 1000);
+
+ mips_hpt_frequency = pll_freq / 2 * 1000;
+
+ clocksource_mips.rating = 200 + mips_hpt_frequency / 10000000;
+
+ clocksource_set_clock(&clocksource_mips, mips_hpt_frequency);
+
+ clocksource_register(&clocksource_mips);
+}
+
+/**
+ * struct tim_c - free running counter
+ * @hi: High 16 bits of the counter
+ * @lo: Low 32 bits of the counter
+ *
+ * Lays out the structure of the free running counter in memory. This counter
+ * increments at a rate of 27 MHz/8 on all platforms.
+ */
+struct tim_c {
+ unsigned int hi;
+ unsigned int lo;
+};
+
+static struct tim_c *tim_c;
+
+static cycle_t tim_c_read(struct clocksource *cs)
+{
+ unsigned int hi;
+ unsigned int next_hi;
+ unsigned int lo;
+
+ hi = readl(&tim_c->hi);
+
+ for (;;) {
+ lo = readl(&tim_c->lo);
+ next_hi = readl(&tim_c->hi);
+ if (next_hi == hi)
+ break;
+ hi = next_hi;
+ }
+
+pr_crit("%s: read %llx\n", __func__, ((u64) hi << 32) | lo);
+ return ((u64) hi << 32) | lo;
+}
+
+#define TIM_C_SIZE 48 /* # bits in the timer */
+
+static struct clocksource clocksource_tim_c = {
+ .name = "powertv-tim_c",
+ .read = tim_c_read,
+ .mask = CLOCKSOURCE_MASK(TIM_C_SIZE),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+/**
+ * powertv_tim_c_clocksource_init - set up a clock source for the TIM_C clock
+ *
+ * The hard part here is coming up with a constant k and shift s such that
+ * the 48-bit TIM_C value multiplied by k doesn't overflow and that value,
+ * when shifted right by s, yields the corresponding number of nanoseconds.
+ * We know that TIM_C counts at 27 MHz/8, so each cycle corresponds to
+ * 1 / (27,000,000/8) seconds. Multiply that by a billion and you get the
+ * number of nanoseconds. Since the TIM_C value has 48 bits and the math is
+ * done in 64 bits, avoiding an overflow means that k must be less than
+ * 64 - 48 = 16 bits.
+ */
+static void __init powertv_tim_c_clocksource_init(void)
+{
+ int prescale;
+ unsigned long dividend;
+ unsigned long k;
+ int s;
+ const int max_k_bits = (64 - 48) - 1;
+ const unsigned long billion = 1000000000;
+ const unsigned long counts_per_second = 27000000 / 8;
+
+ prescale = BITS_PER_LONG - ilog2(billion) - 1;
+ dividend = billion << prescale;
+ k = dividend / counts_per_second;
+ s = ilog2(k) - max_k_bits;
+
+ if (s < 0)
+ s = prescale;
+
+ else {
+ k >>= s;
+ s += prescale;
+ }
+
+ clocksource_tim_c.mult = k;
+ clocksource_tim_c.shift = s;
+ clocksource_tim_c.rating = 200;
+
+ clocksource_register(&clocksource_tim_c);
+ tim_c = (struct tim_c *) asic_reg_addr(tim_ch);
+}
+
+/**
+ powertv_clocksource_init - initialize all clocksources
+ */
+void __init powertv_clocksource_init(void)
+{
+ powertv_c0_hpt_clocksource_init();
+ powertv_tim_c_clocksource_init();
+}