Hi GregKH, Can you please take a look at this patch?
Thanks, Shenwei > -----Original Message----- > From: linux-arm-kernel [mailto:linux-arm-kernel-boun...@lists.infradead.org] > On > Behalf Of Shenwei Wang > Sent: 2015年7月30日 11:11 > To: gre...@linuxfoundation.org; a...@arndb.de > Cc: Huang Yongcai-B20788; linux-arm-ker...@lists.infradead.org > Subject: [PATCH v3 1/1] misc: sram: add dev_pm_ops to support module power > gate > > When system goes into low power states like SUSPEND_MEM and HIBERNATION, > the hardware IP block may be powered off to reduce the power consumption. > This power down will lost all the data inside the ram. This patch added the > dev_pm_ops and implemented two callbacks: suspend_noirq and resume_noirq, > which will save the data in the on-chip-ram right before power down and > restore > it after system resumes. > > A new property string named "can-power-gate" is added to the devicetree > bindings too. > > Signed-off-by: Shenwei Wang <shenwei.w...@freescale.com> > Signed-off-by: Anson Huang <b20...@freescale.com> > --- > Change log: > > PATCH v3 > Removed the unnecessary clk_enable/clk_disable. > > PATCH v2 > Use vmalloc to allocate the SRAM backup memory. > Code clean up. > > Documentation/devicetree/bindings/misc/sram.txt | 2 ++ > drivers/misc/sram.c | 42 > +++++++++++++++++++++++++ > 2 files changed, 44 insertions(+) > > diff --git a/Documentation/devicetree/bindings/misc/sram.txt > b/Documentation/devicetree/bindings/misc/sram.txt > index 36cbe5a..1170086 100644 > --- a/Documentation/devicetree/bindings/misc/sram.txt > +++ b/Documentation/devicetree/bindings/misc/sram.txt > @@ -33,6 +33,8 @@ Optional properties in the area nodes: > > - compatible : standard definition, should contain a vendor specific string > in the form <vendor>,[<device>-]<usage> > +- can-power-gate: a property to tell the driver that the sram can support > + power gate > > Example: > > diff --git a/drivers/misc/sram.c b/drivers/misc/sram.c index 15c33cc..db9f1fa > 100644 > --- a/drivers/misc/sram.c > +++ b/drivers/misc/sram.c > @@ -30,7 +30,9 @@ > > struct sram_dev { > struct device *dev; > + void *power_off_save; > void __iomem *virt_base; > + u32 size; > > struct gen_pool *pool; > struct clk *clk; > @@ -156,6 +158,33 @@ static int sram_reserve_regions(struct sram_dev > *sram, struct resource *res) > return ret; > } > > +static int sram_suspend_noirq(struct device *dev) { > + struct platform_device *pdev = to_platform_device(dev); > + struct sram_dev *sram = platform_get_drvdata(pdev); > + > + if (!sram->power_off_save) > + return 0; > + > + /* Save necessary regs */ > + memcpy(sram->power_off_save, sram->virt_base, sram->size); > + > + return 0; > +} > + > +static int sram_resume_noirq(struct device *dev) { > + struct platform_device *pdev = to_platform_device(dev); > + struct sram_dev *sram = platform_get_drvdata(pdev); > + > + if (!sram->power_off_save) > + return 0; > + > + memcpy(sram->virt_base, sram->power_off_save, sram->size); > + > + return 0; > +} > + > static int sram_probe(struct platform_device *pdev) { > struct sram_dev *sram; > @@ -176,6 +205,7 @@ static int sram_probe(struct platform_device *pdev) > } > > size = resource_size(res); > + sram->size = size; > > if (!devm_request_mem_region(sram->dev, res->start, size, pdev->name)) { > dev_err(sram->dev, "could not request region for resource\n"); > @@ > -203,6 +233,9 @@ static int sram_probe(struct platform_device *pdev) > > platform_set_drvdata(pdev, sram); > > + if (of_property_read_bool(pdev->dev.of_node, "can-power-gate")) > + sram->power_off_save = vmalloc(size); > + > dev_dbg(sram->dev, "SRAM pool: %zu KiB @ 0x%p\n", > gen_pool_size(sram->pool) / 1024, sram->virt_base); > > @@ -219,6 +252,9 @@ static int sram_remove(struct platform_device *pdev) > if (sram->clk) > clk_disable_unprepare(sram->clk); > > + if (sram->power_off_save) > + vfree(sram->power_off_save); > + > return 0; > } > > @@ -229,10 +265,16 @@ static const struct of_device_id sram_dt_ids[] = { }; > #endif > > +static const struct dev_pm_ops sram_pm_ops = { > + .suspend_noirq = sram_suspend_noirq, > + .resume_noirq = sram_resume_noirq, > +}; > + > static struct platform_driver sram_driver = { > .driver = { > .name = "sram", > .of_match_table = of_match_ptr(sram_dt_ids), > + .pm = &sram_pm_ops, > }, > .probe = sram_probe, > .remove = sram_remove, > -- > 2.5.0.rc2 > > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-ker...@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
