diff options
Diffstat (limited to 'drivers/clk')
| -rw-r--r-- | drivers/clk/sunxi/clk-sun9i-core.c | 57 |
1 files changed, 29 insertions, 28 deletions
diff --git a/drivers/clk/sunxi/clk-sun9i-core.c b/drivers/clk/sunxi/clk-sun9i-core.c index 9b5e7a1..d8da77d 100644 --- a/drivers/clk/sunxi/clk-sun9i-core.c +++ b/drivers/clk/sunxi/clk-sun9i-core.c @@ -24,50 +24,51 @@ /** - * sun9i_a80_get_pll4_factors() - calculates n, p, m factors for PLL1 + * sun9i_a80_get_pll4_factors() - calculates n, p, m factors for PLL4 * PLL4 rate is calculated as follows * rate = (parent_rate * n >> p) / (m + 1); - * parent_rate is always 24Mhz + * parent_rate is always 24MHz * * p and m are named div1 and div2 in Allwinner's SDK */ static void sun9i_a80_get_pll4_factors(u32 *freq, u32 parent_rate, - u8 *n, u8 *k, u8 *m, u8 *p) + u8 *n_ret, u8 *k, u8 *m_ret, u8 *p_ret) { - int div; + int n; + int m = 1; + int p = 1; - /* Normalize value to a 6M multiple */ - div = DIV_ROUND_UP(*freq, 6000000); + /* Normalize value to a 6 MHz multiple (24 MHz / 4) */ + n = DIV_ROUND_UP(*freq, 6000000); - /* divs above 256 cannot be odd */ - if (div > 256) - div = round_up(div, 2); + /* If n is too large switch to steps of 12 MHz */ + if (n > 255) { + m = 0; + n = (n + 1) / 2; + } + + /* If n is still too large switch to steps of 24 MHz */ + if (n > 255) { + p = 0; + n = (n + 1) / 2; + } - /* divs above 512 must be a multiple of 4 */ - if (div > 512) - div = round_up(div, 4); + /* n must be between 12 and 255 */ + if (n > 255) + n = 255; + else if (n < 12) + n = 12; - *freq = 6000000 * div; + *freq = ((24000000 * n) >> p) / (m + 1); /* we were called to round the frequency, we can now return */ - if (n == NULL) + if (n_ret == NULL) return; - /* p will be 1 for divs under 512 */ - if (div < 512) - *p = 1; - else - *p = 0; - - /* m will be 1 if div is odd */ - if (div & 1) - *m = 1; - else - *m = 0; - - /* calculate a suitable n based on m and p */ - *n = div / (*p + 1) / (*m + 1); + *n_ret = n; + *m_ret = m; + *p_ret = p; } static struct clk_factors_config sun9i_a80_pll4_config = { |
