diff options
Diffstat (limited to 'drivers/clk/mvebu/common.c')
| -rw-r--r-- | drivers/clk/mvebu/common.c | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/drivers/clk/mvebu/common.c b/drivers/clk/mvebu/common.c index 8145c4efc381..7f8a33ab265b 100644 --- a/drivers/clk/mvebu/common.c +++ b/drivers/clk/mvebu/common.c @@ -26,8 +26,85 @@ * Core Clocks */ +#define SSCG_CONF_MODE(reg) (((reg) >> 16) & 0x3) +#define SSCG_SPREAD_DOWN 0x0 +#define SSCG_SPREAD_UP 0x1 +#define SSCG_SPREAD_CENTRAL 0x2 +#define SSCG_CONF_LOW(reg) (((reg) >> 8) & 0xFF) +#define SSCG_CONF_HIGH(reg) ((reg) & 0xFF) + static struct clk_onecell_data clk_data; +/* + * This function can be used by the Kirkwood, the Armada 370, the + * Armada XP and the Armada 375 SoC. The name of the function was + * chosen following the dt convention: using the first known SoC + * compatible with it. + */ +u32 kirkwood_fix_sscg_deviation(struct device_node *np, u32 system_clk) +{ + struct device_node *sscg_np = NULL; + void __iomem *sscg_map; + u32 sscg_reg; + s32 low_bound, high_bound; + u64 freq_swing_half; + + sscg_np = of_find_node_by_name(np, "sscg"); + if (sscg_np == NULL) { + pr_err("cannot get SSCG register node\n"); + return system_clk; + } + + sscg_map = of_iomap(sscg_np, 0); + if (sscg_map == NULL) { + pr_err("cannot map SSCG register\n"); + goto out; + } + + sscg_reg = readl(sscg_map); + high_bound = SSCG_CONF_HIGH(sscg_reg); + low_bound = SSCG_CONF_LOW(sscg_reg); + + if ((high_bound - low_bound) <= 0) + goto out; + /* + * From Marvell engineer we got the following formula (when + * this code was written, the datasheet was erroneous) + * Spread percentage = 1/96 * (H - L) / H + * H = SSCG_High_Boundary + * L = SSCG_Low_Boundary + * + * As the deviation is half of spread then it lead to the + * following formula in the code. + * + * To avoid an overflow and not lose any significant digit in + * the same time we have to use a 64 bit integer. + */ + + freq_swing_half = (((u64)high_bound - (u64)low_bound) + * (u64)system_clk); + do_div(freq_swing_half, (2 * 96 * high_bound)); + + switch (SSCG_CONF_MODE(sscg_reg)) { + case SSCG_SPREAD_DOWN: + system_clk -= freq_swing_half; + break; + case SSCG_SPREAD_UP: + system_clk += freq_swing_half; + break; + case SSCG_SPREAD_CENTRAL: + default: + break; + } + + iounmap(sscg_map); + +out: + of_node_put(sscg_np); + + return system_clk; +} + void __init mvebu_coreclk_setup(struct device_node *np, const struct coreclk_soc_desc *desc) { @@ -62,6 +139,11 @@ void __init mvebu_coreclk_setup(struct device_node *np, of_property_read_string_index(np, "clock-output-names", 1, &cpuclk_name); rate = desc->get_cpu_freq(base); + + if (desc->is_sscg_enabled && desc->fix_sscg_deviation + && desc->is_sscg_enabled(base)) + rate = desc->fix_sscg_deviation(np, rate); + clk_data.clks[1] = clk_register_fixed_rate(NULL, cpuclk_name, NULL, CLK_IS_ROOT, rate); WARN_ON(IS_ERR(clk_data.clks[1])); |