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Diffstat (limited to 'arch/mips/kernel/csrc-powertv.c')
| -rw-r--r-- | arch/mips/kernel/csrc-powertv.c | 180 |
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(); +} |