[PATCH 3/6] clk: bcm2835: enable clocks that have been enabled by firmware
kernel at martin.sperl.org
kernel at martin.sperl.org
Mon Feb 29 03:39:19 PST 2016
From: Martin Sperl <kernel at martin.sperl.org>
If a clock that has been enabled by the firmware gets disabled
by a driver this may right now result in a crash of the system
as then also the corresponding PLL_dividers as well as PLLs
get disabled (if not used) - some of which are used by the
VideoCore GPU (which also runs the firmware)
This patch prepares/enables those clocks that have been
configured by the firmware.
Whenever the clock framework implements either
CLK_IS_CRITICAL or HAND_OFF this can get changed to use this
new mechanism.
For this to be completely successful (i.e not missing a clock
and subsequently a pll) it is recommended to add all the known
clocks of the soc so that this can get applied to all clocks.
Signed-off-by: Martin Sperl <kernel at martin.sperl.org>
---
drivers/clk/bcm/clk-bcm2835.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c
index 30d6486..1fbb55d 100644
--- a/drivers/clk/bcm/clk-bcm2835.c
+++ b/drivers/clk/bcm/clk-bcm2835.c
@@ -37,6 +37,7 @@
* generator).
*/
+#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/clkdev.h>
#include <linux/clk/bcm2835.h>
@@ -1478,6 +1479,7 @@ static struct clk *bcm2835_register_clock(struct bcm2835_cprman *cprman,
struct clk_init_data init;
const char *parents[1 << CM_SRC_BITS];
size_t i;
+ struct clk *clk;
/*
* Replace our "xosc" references with the oscillator's
@@ -1511,7 +1513,18 @@ static struct clk *bcm2835_register_clock(struct bcm2835_cprman *cprman,
clock->data = data;
clock->hw.init = &init;
- return devm_clk_register(cprman->dev, &clock->hw);
+ clk = devm_clk_register(cprman->dev, &clock->hw);
+ if (IS_ERR_OR_NULL(clk))
+ return clk;
+
+ /* enable/prepare if the clock is enabled by the firmware */
+ if (cprman_read(cprman, data->ctl_reg) & CM_ENABLE) {
+ dev_info(cprman->dev,
+ "found firmware enabled clock %pC\n", clk);
+ clk_prepare_enable(clk);
+ }
+
+ return clk;
}
static int bcm2835_clk_probe(struct platform_device *pdev)
--
1.7.10.4
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