summaryrefslogtreecommitdiffstats
path: root/firmware/target/arm/imx233/clkctrl-imx233.c
diff options
context:
space:
mode:
authorAmaury Pouly <amaury.pouly@gmail.com>2014-03-08 18:49:13 +0100
committerAmaury Pouly <amaury.pouly@gmail.com>2014-03-08 18:51:54 +0100
commit1f3979821c952a32ff4b9ca7ca229a8d78775bf9 (patch)
tree72ed649a47a64186b1e5546b3a9a7d2386f261b4 /firmware/target/arm/imx233/clkctrl-imx233.c
parent3e2f3efd894e7cbe80d9f1877f4a8babba5ce052 (diff)
downloadrockbox-1f3979821c952a32ff4b9ca7ca229a8d78775bf9.tar.gz
rockbox-1f3979821c952a32ff4b9ca7ca229a8d78775bf9.tar.bz2
rockbox-1f3979821c952a32ff4b9ca7ca229a8d78775bf9.zip
imx233: add function to change cpu/hbus frequency safely
Change-Id: I88e9ad54ba65846ae4d94ae03009b3656f2489f2
Diffstat (limited to 'firmware/target/arm/imx233/clkctrl-imx233.c')
-rw-r--r--firmware/target/arm/imx233/clkctrl-imx233.c32
1 files changed, 32 insertions, 0 deletions
diff --git a/firmware/target/arm/imx233/clkctrl-imx233.c b/firmware/target/arm/imx233/clkctrl-imx233.c
index a5ca61c1c7..2f507b076a 100644
--- a/firmware/target/arm/imx233/clkctrl-imx233.c
+++ b/firmware/target/arm/imx233/clkctrl-imx233.c
@@ -189,6 +189,38 @@ bool imx233_clkctrl_get_bypass(enum imx233_clock_t clk)
default: return false;
}
}
+
+void imx233_clkctrl_set_cpu_hbus_div(int cpu_idiv, int cpu_fdiv, int hbus_div)
+{
+ /* disable interrupts to avoid an IRQ being triggered at the point
+ * where we are slow/weird speeds, that would result in massive slow-down... */
+ int oldstatus = disable_interrupt_save(IRQ_FIQ_STATUS);
+ /* we need to be very careful here: putting the wrong dividers could blow-up the
+ * frequency and result in crash, also the cpu could be running from XTAL or
+ * PLL at this point */
+ int old_cpu_fdiv = imx233_clkctrl_get_frac_div(CLK_CPU);
+ int old_hbus_div = imx233_clkctrl_get_div(CLK_HBUS);
+ /* since HBUS is tied to cpu, we first ensure that the HBUS is safe to handle
+ * both old and new speed: take maximum of old and new dividers */
+ if(hbus_div > old_hbus_div)
+ imx233_clkctrl_set_div(CLK_HBUS, hbus_div);
+ /* we are about to change cpu speed: we first ensure that the fractional
+ * divider is safe to handle both old and new integer divided frequency: take max */
+ if(cpu_fdiv > old_cpu_fdiv)
+ imx233_clkctrl_set_frac_div(CLK_CPU, cpu_fdiv);
+ /* we are safe for major divider change */
+ imx233_clkctrl_set_div(CLK_CPU, cpu_idiv);
+ /* if the final fractional divider is lower than previous one, it's time to switch */
+ if(cpu_fdiv < old_cpu_fdiv)
+ imx233_clkctrl_set_frac_div(CLK_CPU, cpu_fdiv);
+ /* if we were running from XTAL, switch to PLL */
+ imx233_clkctrl_set_bypass(CLK_CPU, false);
+ /* finally restore HBUS to its proper value */
+ if(hbus_div < old_hbus_div)
+ imx233_clkctrl_set_div(CLK_HBUS, hbus_div);
+ /* we are free again */
+ restore_interrupt(oldstatus);
+}
#endif
void imx233_clkctrl_enable_usb(bool enable)