[PATCH v5 08/20] clk: bcm2835: add fractional support
From: kernel at martin.sperl.org <hidden>
Date: 2016-02-28 15:36:59
Also in:
linux-clk
Subsystem:
common clk framework, the rest · Maintainers:
Michael Turquette, Stephen Boyd, Linus Torvalds
From: Martin Sperl <redacted> The current driver calculates the clock divider with fractional support enabled. But it does not enable fractional support in the control register. This patch enables fractional support in the control register whenever there is a fractional bit set in the requested clock divider. Signed-off-by: Martin Sperl <redacted> --- drivers/clk/bcm/clk-bcm2835.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)
diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c
index 144d5d5..ffc5b3c 100644
--- a/drivers/clk/bcm/clk-bcm2835.c
+++ b/drivers/clk/bcm/clk-bcm2835.c@@ -49,6 +49,7 @@ #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
@@ -126,6 +127,7 @@ # 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
@@ -875,9 +877,26 @@ 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; }
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1.7.10.4