diff options
Diffstat (limited to 'drivers/clk/bcm')
| -rw-r--r-- | drivers/clk/bcm/clk-bcm2835.c | 45 |
1 files changed, 39 insertions, 6 deletions
diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c index 1fee1fd87cea..1ee9a3549473 100644 --- a/drivers/clk/bcm/clk-bcm2835.c +++ b/drivers/clk/bcm/clk-bcm2835.c @@ -51,6 +51,7 @@ #define CM_GNRICCTL 0x000 #define CM_GNRICDIV 0x004 # define CM_DIV_FRAC_BITS 12 +# define CM_DIV_FRAC_MASK GENMASK(CM_DIV_FRAC_BITS - 1, 0) #define CM_VPUCTL 0x008 #define CM_VPUDIV 0x00c @@ -128,6 +129,7 @@ # define CM_GATE BIT(CM_GATE_BIT) # define CM_BUSY BIT(7) # define CM_BUSYD BIT(8) +# define CM_FRAC BIT(9) # define CM_SRC_SHIFT 0 # define CM_SRC_BITS 4 # define CM_SRC_MASK 0xf @@ -644,6 +646,7 @@ struct bcm2835_clock_data { u32 frac_bits; bool is_vpu_clock; + bool is_mash_clock; }; static const char *const bcm2835_clock_per_parents[] = { @@ -825,6 +828,7 @@ static const struct bcm2835_clock_data bcm2835_clock_pwm_data = { .div_reg = CM_PWMDIV, .int_bits = 12, .frac_bits = 12, + .is_mash_clock = true, }; struct bcm2835_pll { @@ -1180,7 +1184,7 @@ static u32 bcm2835_clock_choose_div(struct clk_hw *hw, GENMASK(CM_DIV_FRAC_BITS - data->frac_bits, 0) >> 1; u64 temp = (u64)parent_rate << CM_DIV_FRAC_BITS; u64 rem; - u32 div; + u32 div, mindiv, maxdiv; rem = do_div(temp, rate); div = temp; @@ -1190,11 +1194,23 @@ static u32 bcm2835_clock_choose_div(struct clk_hw *hw, div += unused_frac_mask + 1; div &= ~unused_frac_mask; - /* clamp to min divider of 1 */ - div = max_t(u32, div, 1 << CM_DIV_FRAC_BITS); - /* clamp to the highest possible fractional divider */ - div = min_t(u32, div, GENMASK(data->int_bits + CM_DIV_FRAC_BITS - 1, - CM_DIV_FRAC_BITS - data->frac_bits)); + /* different clamping limits apply for a mash clock */ + if (data->is_mash_clock) { + /* clamp to min divider of 2 */ + mindiv = 2 << CM_DIV_FRAC_BITS; + /* clamp to the highest possible integer divider */ + maxdiv = (BIT(data->int_bits) - 1) << CM_DIV_FRAC_BITS; + } else { + /* clamp to min divider of 1 */ + mindiv = 1 << CM_DIV_FRAC_BITS; + /* clamp to the highest possible fractional divider */ + maxdiv = GENMASK(data->int_bits + CM_DIV_FRAC_BITS - 1, + CM_DIV_FRAC_BITS - data->frac_bits); + } + + /* apply the clamping limits */ + div = max_t(u32, div, mindiv); + div = min_t(u32, div, maxdiv); return div; } @@ -1288,9 +1304,26 @@ static int bcm2835_clock_set_rate(struct clk_hw *hw, struct bcm2835_cprman *cprman = clock->cprman; const struct bcm2835_clock_data *data = clock->data; u32 div = bcm2835_clock_choose_div(hw, rate, parent_rate, false); + u32 ctl; + + spin_lock(&cprman->regs_lock); + + /* + * Setting up frac support + * + * In principle it is recommended to stop/start the clock first, + * but as we set CLK_SET_RATE_GATE during registration of the + * clock this requirement should be take care of by the + * clk-framework. + */ + ctl = cprman_read(cprman, data->ctl_reg) & ~CM_FRAC; + ctl |= (div & CM_DIV_FRAC_MASK) ? CM_FRAC : 0; + cprman_write(cprman, data->ctl_reg, ctl); cprman_write(cprman, data->div_reg, div); + spin_unlock(&cprman->regs_lock); + return 0; } |