MIPS: PowerTV: Base files for Cisco PowerTV platform

Add the Cisco Powertv cable settop box to the MIPS tree. This platform is
based on a MIPS 24Kc processor with various devices integrated on the same
ASIC. There are multiple models of this box, with differing configuration
but the same kernel runs across the product line.

Signed-off-by: David VomLehn <dvomlehn@cisco.com>
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/132/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 180 insertions, 0 deletions

diff --git a/arch/mips/kernel/csrc-powertv.c b/arch/mips/kernel/csrc-powertv.c
new file mode 100644
index 000000000000..a27c16c8690e
--- /dev/null
+++ b/arch/mips/kernel/csrc-powertv.c
@@ -0,0 +1,180 @@
+/*
+ * 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();
+}