Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754104Ab1BSLad (ORCPT ); Sat, 19 Feb 2011 06:30:33 -0500 Received: from devils.ext.ti.com ([198.47.26.153]:50108 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752662Ab1BSLaa convert rfc822-to-8bit (ORCPT ); Sat, 19 Feb 2011 06:30:30 -0500 From: "TK, Pratheesh Gangadhar" To: "Hans J. Koch" CC: "davinci-linux-open-source@linux.davincidsp.com" , "gregkh@suse.de" , "Chatterjee, Amit" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" Date: Sat, 19 Feb 2011 17:00:12 +0530 Subject: RE: [PATCH 1/2] PRUSS UIO driver support Thread-Topic: [PATCH 1/2] PRUSS UIO driver support Thread-Index: AcvPiVm7T6RLx76kTmiz3S6GTY+hlAAlq1Cw Message-ID: References: <1298041530-26855-1-git-send-email-pratheesh@ti.com> <1298041530-26855-2-git-send-email-pratheesh@ti.com> <20110218163147.GD4684@local> In-Reply-To: <20110218163147.GD4684@local> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5863 Lines: 149 > -----Original Message----- > From: Hans J. Koch [mailto:hjk@hansjkoch.de] > Sent: Friday, February 18, 2011 10:02 PM > To: TK, Pratheesh Gangadhar > Cc: davinci-linux-open-source@linux.davincidsp.com; hjk@hansjkoch.de; > gregkh@suse.de; Chatterjee, Amit; linux-kernel@vger.kernel.org; linux-arm- > kernel@lists.infradead.org > Subject: Re: [PATCH 1/2] PRUSS UIO driver support > > On Fri, Feb 18, 2011 at 08:35:29PM +0530, Pratheesh Gangadhar wrote: > > Signed-off-by: Pratheesh Gangadhar > > > > This patch implements PRUSS (Programmable Real-time Unit Sub System) > > UIO driver which exports SOC resources associated with PRUSS like > > I/O, memories and IRQs to user space. PRUSS is dual 32-bit RISC > > processors which is efficient in performing embedded tasks that > > require manipulation of packed memory mapped data structures and > > efficient in handling system events that have tight real time > > constraints. This driver is currently supported on Texas Instruments > > DA850, AM18xx and OMAPL1-38 devices. > > For example, PRUSS runs firmware for real-time critical industrial > > communication data link layer and communicates with application stack > > running in user space via shared memory and IRQs. > > I see a few issues, comments below. > > Thanks, > Hans > > > --- > > drivers/uio/Kconfig | 10 ++ > > drivers/uio/Makefile | 1 + > > drivers/uio/uio_pruss.c | 250 > +++++++++++++++++++++++++++++++++++++++++++++++ > > 3 files changed, 261 insertions(+), 0 deletions(-) > > create mode 100644 drivers/uio/uio_pruss.c > > > > diff --git a/drivers/uio/Kconfig b/drivers/uio/Kconfig > > index bb44079..631ffe3 100644 > > --- a/drivers/uio/Kconfig > > +++ b/drivers/uio/Kconfig > > @@ -94,4 +94,14 @@ config UIO_NETX > > To compile this driver as a module, choose M here; the module > > will be called uio_netx. > > > > +config UIO_PRUSS > > + tristate "Texas Instruments PRUSS driver" > > + depends on ARCH_DAVINCI_DA850 > > + default n > > That line is unneccessary, "n" is already the default. > Ok, will fix in the next version. > > + help > > + PRUSS driver for OMAPL138/DA850/AM18XX devices > > + PRUSS driver requires user space components > > + To compile this driver as a module, choose M here: the module > > + will be called uio_pruss. > > + > > endif > > +#define MAX_PRUSS_EVTOUT_INSTANCE (8) > > The brackets are not needed. > Will fix in the next version. > > + > > +static struct clk *pruss_clk; > > +static struct uio_info *info[MAX_PRUSS_EVTOUT_INSTANCE]; > > is it really neccessary to allocate that statically? > > > +static void *ddr_virt_addr; > > +static dma_addr_t ddr_phy_addr; > > + Agree - not necessary - will fix. > > +static irqreturn_t pruss_handler(int irq, struct uio_info *dev_info) > > +{ > > + return IRQ_HANDLED; > > +} > > ROTFL. That reminds me of an old story. The last time I wrote this, and > Greg dared to post it, we received this reply: > > http://marc.info/?l=linux-kernel&m=116604101232144&w=2 > > So, if you really have a _very_ good reason why this _always_ works on > _any_ DA850 board, add a comment that explains why. Otherwise the whole > patch set will be doomed. > It always worked for me during the tests on the h/w. So did not bother to dig into the details then. From AM1808/AM1810 ARM Microprocessor System Reference Guide (http://focus.ti.com/general/docs/lit/getliterature.tsp?literatureNumber=sprugm9a&fileType=pdf), section 11.3.1 Interrupt processing The interrupt processing block does the following tasks: -Synchronization of slower and asynchronous interrupts - Conversion of polarity to active high - Conversion of interrupt type to pulse interrupts After the processing block, all interrupts will be active-high pulses Interrupt processing is the first step in INTC h/w which maps system interrupts to ARM (host) interrupts (FIQ, IRQ). However I am willing to clean this up to meet the kernel guidelines and good practices... > > + > > +static int __devinit pruss_probe(struct platform_device *dev) > > +{ > > + int ret = -ENODEV; > > + int count = 0; > > + struct resource *regs_pruram, *regs_l3ram, *regs_ddr; > > + char *string; > > + for (count = 0; count < MAX_PRUSS_EVTOUT_INSTANCE; count++) { > > + info[count]->mem[0].addr = regs_pruram->start; > > + info[count]->mem[0].size = > > + regs_pruram->end - regs_pruram->start + 1; > > + if (!info[count]->mem[0].addr > > + || !(info[count]->mem[0].size - 1)) { > > That size check looks fishy. If somebody forgot to set the size it's OK ? > size is set just previous line, right? If regs_prum_ram->end== regs_prum_ram->start - then there is something wrong... > > + dev_err(&dev->dev, "Invalid memory resource\n"); > > + break; > > + } > > + info[count]->mem[0].internal_addr = > > + ioremap(regs_pruram->start, info[count]->mem[0].size); > > + if (!info[count]->mem[0].internal_addr) { > > + dev_err(&dev->dev, > > + "Can't remap memory address range\n"); > > + break; > > + } > > + /* Register PRUSS IRQ lines */ > > + info[count]->irq = IRQ_DA8XX_EVTOUT0 + count; > > + > > + info[count]->irq_flags = IRQF_SHARED; > > How do you handle shared interrupts with the handler above? > > > + info[count]->handler = pruss_handler; > > And how do you make sure your interrupts are not level triggered? The > handler above will hang for level triggered interrupts. As mentioned above interrupt controller (ARM INTC) converts interrupt type to pulse. After required processing is complete - user space handler clears the interrupt from PRUSS. Thanks, Pratheesh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/