From: Guenter Roeck <linux@roeck-us.net>
To: Peter Crosthwaite <crosthwaitepeter@gmail.com>,
Peter Maydell <peter.maydell@linaro.org>,
Nathan Rossi <nathan@nathanrossi.com>,
Alistair Francis <alistair.francis@xilinx.com>
Cc: "qemu-devel@nongnu.org Developers" <qemu-devel@nongnu.org>,
Peter Crosthwaite <crosthwaite.peter@gmail.com>
Subject: Re: [Qemu-devel] [PATCH v2] hw/misc/zynq_slcr: Change CPU clock rate for Linux boots
Date: Sun, 13 Sep 2015 13:37:08 -0700 [thread overview]
Message-ID: <55F5DE74.9060002@roeck-us.net> (raw)
In-Reply-To: <CAPokK=q31zFv-XT1PjHNAidS3wmPs1C=02J+AkDXyL4NFG3wDg@mail.gmail.com>
On 09/13/2015 01:22 PM, Peter Crosthwaite wrote:
> On Sat, Sep 12, 2015 at 2:06 PM, Guenter Roeck <linux@roeck-us.net> wrote:
>> The Linux kernel only accepts 333334 Khz and 666667 Khz clock rates, and
>> may crash if the actual clock rate is too low. The clock rate used to be
>> (ps-clk-frequency * 26 / 4), which resulted in a CPU frequency of
>> 216666 Khz if ps-clk-frequency was set to 33333333 Hz. Change it to
>> (ps-clk-frequency * 20 / 2) = 333333 Khz for to make Linux happy.
>> Limit the change to Linux boots only.
>>
>> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
>>
>
> Reviewed-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
>
> Can this go via target-arm? (cc PMM).
>
> There may be more changes worth making on is_linux. I don't have the
> patch with the full list of FSBL-related SLCR changes handy and can't
> seem to find it in any modern Yocto trees. Wondering if Yocto still
> supports booting Zynq without FSBL (Nathan/Alistair may know more)?
>
Good question. I didn't find any related patches in Yocto 1.8,
but on the other side I wasn't sure if I was looking in the right place.
Guenter
> Regards,
> Peter
>
>> ---
>> v2: Limit scope of change to Linux boots.
>>
>> hw/misc/zynq_slcr.c | 29 +++++++++++++++++++++++++++--
>> 1 file changed, 27 insertions(+), 2 deletions(-)
>>
>> diff --git a/hw/misc/zynq_slcr.c b/hw/misc/zynq_slcr.c
>> index 964f253..ed510fb 100644
>> --- a/hw/misc/zynq_slcr.c
>> +++ b/hw/misc/zynq_slcr.c
>> @@ -14,6 +14,7 @@
>> * with this program; if not, see <http://www.gnu.org/licenses/>.
>> */
>>
>> +#include "hw/arm/linux-boot-if.h"
>> #include "hw/hw.h"
>> #include "qemu/timer.h"
>> #include "hw/sysbus.h"
>> @@ -177,6 +178,8 @@ typedef struct ZynqSLCRState {
>>
>> MemoryRegion iomem;
>>
>> + bool is_linux;
>> +
>> uint32_t regs[ZYNQ_SLCR_NUM_REGS];
>> } ZynqSLCRState;
>>
>> @@ -189,7 +192,11 @@ static void zynq_slcr_reset(DeviceState *d)
>>
>> s->regs[LOCKSTA] = 1;
>> /* 0x100 - 0x11C */
>> - s->regs[ARM_PLL_CTRL] = 0x0001A008;
>> + if (!s->is_linux) {
>> + s->regs[ARM_PLL_CTRL] = 0x0001A008;
>> + } else {
>> + s->regs[ARM_PLL_CTRL] = 0x00014008;
>> + }
>> s->regs[DDR_PLL_CTRL] = 0x0001A008;
>> s->regs[IO_PLL_CTRL] = 0x0001A008;
>> s->regs[PLL_STATUS] = 0x0000003F;
>> @@ -198,7 +205,11 @@ static void zynq_slcr_reset(DeviceState *d)
>> s->regs[IO_PLL_CFG] = 0x00014000;
>>
>> /* 0x120 - 0x16C */
>> - s->regs[ARM_CLK_CTRL] = 0x1F000400;
>> + if (!s->is_linux) {
>> + s->regs[ARM_CLK_CTRL] = 0x1F000400;
>> + } else {
>> + s->regs[ARM_CLK_CTRL] = 0x1F000200;
>> + }
>> s->regs[DDR_CLK_CTRL] = 0x18400003;
>> s->regs[DCI_CLK_CTRL] = 0x01E03201;
>> s->regs[APER_CLK_CTRL] = 0x01FFCCCD;
>> @@ -429,17 +440,27 @@ static const VMStateDescription vmstate_zynq_slcr = {
>> .version_id = 2,
>> .minimum_version_id = 2,
>> .fields = (VMStateField[]) {
>> + VMSTATE_BOOL(is_linux, ZynqSLCRState),
>> VMSTATE_UINT32_ARRAY(regs, ZynqSLCRState, ZYNQ_SLCR_NUM_REGS),
>> VMSTATE_END_OF_LIST()
>> }
>> };
>>
>> +static void zynq_sclr_linux_init(ARMLinuxBootIf *obj, bool secure_boot)
>> +{
>> + ZynqSLCRState *s = ZYNQ_SLCR(obj);
>> +
>> + s->is_linux = true;
>> +}
>> +
>> static void zynq_slcr_class_init(ObjectClass *klass, void *data)
>> {
>> DeviceClass *dc = DEVICE_CLASS(klass);
>> + ARMLinuxBootIfClass *albifc = ARM_LINUX_BOOT_IF_CLASS(klass);
>>
>> dc->vmsd = &vmstate_zynq_slcr;
>> dc->reset = zynq_slcr_reset;
>> + albifc->arm_linux_init = zynq_sclr_linux_init;
>> }
>>
>> static const TypeInfo zynq_slcr_info = {
>> @@ -448,6 +469,10 @@ static const TypeInfo zynq_slcr_info = {
>> .parent = TYPE_SYS_BUS_DEVICE,
>> .instance_size = sizeof(ZynqSLCRState),
>> .instance_init = zynq_slcr_init,
>> + .interfaces = (InterfaceInfo []) {
>> + { TYPE_ARM_LINUX_BOOT_IF },
>> + { },
>> + },
>> };
>>
>> static void zynq_slcr_register_types(void)
>> --
>> 2.1.4
>>
>
next prev parent reply other threads:[~2015-09-13 20:37 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-12 21:06 [Qemu-devel] [PATCH v2] hw/misc/zynq_slcr: Change CPU clock rate for Linux boots Guenter Roeck
2015-09-13 20:22 ` Peter Crosthwaite
2015-09-13 20:37 ` Guenter Roeck [this message]
2015-09-13 20:47 ` Peter Maydell
2015-09-13 21:51 ` Guenter Roeck
2015-09-13 22:42 ` Peter Crosthwaite
2015-09-14 12:07 ` Peter Maydell
2015-09-14 13:17 ` Nathan Rossi
2015-09-14 14:05 ` Guenter Roeck
2015-09-27 5:44 ` Peter Crosthwaite
2015-09-27 5:50 ` Peter Crosthwaite
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