Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758499Ab3FTSKR (ORCPT ); Thu, 20 Jun 2013 14:10:17 -0400 Received: from mail-pd0-f181.google.com ([209.85.192.181]:63394 "EHLO mail-pd0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758473Ab3FTSKP (ORCPT ); Thu, 20 Jun 2013 14:10:15 -0400 Message-ID: <51C34584.8070301@gmail.com> Date: Thu, 20 Jun 2013 11:10:12 -0700 From: David Daney User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130514 Thunderbird/17.0.6 MIME-Version: 1.0 To: Linus Walleij CC: linux-mips@linux-mips.org, Ralf Baechle , Grant Likely , Rob Herring , "linux-kernel@vger.kernel.org" , "devicetree-discuss@lists.ozlabs.org" , David Daney Subject: Re: Re: [PATCH] gpio MIPS/OCTEON: Add a driver for OCTEON's on-chip GPIO pins. References: <1371251915-18271-1-git-send-email-ddaney.cavm@gmail.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5731 Lines: 187 Sorry for not responding earlier, but my e-mail system seems to have malfunctioned with respect to this message... On 06/17/2013 01:51 AM, Linus Walleij wrote: > On Sat, Jun 15, 2013 at 1:18 AM, David Daney wrote: > >> From: David Daney >> >> The SOCs in the OCTEON family have 16 (or in some cases 20) on-chip >> GPIO pins, this driver handles them all. Configuring the pins as >> interrupt sources is handled elsewhere (OCTEON's irq handling code). >> >> Signed-off-by: David Daney > >> This patch depends somewhat on patches in Ralf's MIPS/Linux -next tree >> where we have patches that enable the Kconfig CAVIUM_OCTEON_SOC and >> ARCH_REQUIRE_GPIOLIB symbols. Apart from that it is stand-alone and >> is probably suitable for merging via the GPIO tree. > > Really? You're using this: > > +#include > +#include > > I cannot find this in my tree. Weird, I see them here: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/mips/include/asm/octeon/cvmx-gpio-defs.h https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/mips/include/asm/octeon/octeon.h Do you not have these? > > Further I ask why that second file is not part of *this* patch? > It surely seems GPIO-related, and would probably need to > go into include/linux/platform_data/gpio-octeon.h or something > rather than such platform dirs. > > (...) >> +config GPIO_OCTEON >> + tristate "Cavium OCTEON GPIO" >> + depends on GPIOLIB && CAVIUM_OCTEON_SOC > > depend on OF as well right? Or does the CAVIUM_OCTEON_SOC already > imply that? We already have 'select USE_OF', so I think adding OF here would be redundant. > > (...) >> +++ b/drivers/gpio/gpio-octeon.c > > >> +#define RX_DAT 0x80 >> +#define TX_SET 0x88 >> +#define TX_CLEAR 0x90 > > >> +/* >> + * The address offset of the GPIO configuration register for a given >> + * line. >> + */ >> +static unsigned int bit_cfg_reg(unsigned int gpio) > > Maybe the passed variable shall be named "offset" here, as it is named > offset on all call sites, and it surely local for this instance? Well it is the gpio line, so perhaps it should universally be change to "line" or "pin" > >> +{ >> + if (gpio < 16) >> + return 8 * gpio; >> + else >> + return 8 * (gpio - 16) + 0x100; > > Put this 0x100 in the #defines above with the name something like > STRIDE. But it is not a 'STRIDE', it is a discontinuity compensation and used in exactly one place. > >> +struct octeon_gpio { >> + struct gpio_chip chip; >> + u64 register_base; >> +}; > > OMG everything is 64 bit. Well has to come to this I guess. Not everything. This is custom logic in an SoC with 64-bit wide internal address buses, what would you suggest? > >> +static void octeon_gpio_set(struct gpio_chip *chip, unsigned offset, int value) >> +{ >> + struct octeon_gpio *gpio = container_of(chip, struct octeon_gpio, chip); >> + u64 mask = 1ull << offset; > > And now BIT(offset) does not work anymore because it is defined as > #define BIT(nr) (1UL << (nr)) > OK we will have to live with this FTM I guess. > >> +static int octeon_gpio_dir_out(struct gpio_chip *chip, unsigned offset, >> + int value) >> +{ >> + struct octeon_gpio *gpio = container_of(chip, struct octeon_gpio, chip); >> + union cvmx_gpio_bit_cfgx cfgx; >> + >> + octeon_gpio_set(chip, offset, value); >> + >> + cfgx.u64 = 0; >> + cfgx.s.tx_oe = 1; > > This makes me want to review that magic header file of yours, > I guess this comes from ? Not really magic, but yes that is where it comes from. > > Should not this latter variable be a bool? I don't think so, it is not the result of a comparison operator. > > I'm not a fan of packed bitfields like this, I prefer if you just > OR | and AND & the bits together in the driver. > >> +static int octeon_gpio_get(struct gpio_chip *chip, unsigned offset) >> +{ >> + struct octeon_gpio *gpio = container_of(chip, struct octeon_gpio, chip); >> + u64 read_bits = cvmx_read_csr(gpio->register_base + RX_DAT); >> + >> + return ((1ull << offset) & read_bits) != 0; > > A common idiom we use for this is: > > return !!(read_bits & (1ull << offset)); I hate that idiom, but if its use is a condition of accepting the patch, I will change it. > >> + pdev->dev.platform_data = chip; >> + chip->label = "octeon-gpio"; >> + chip->dev = &pdev->dev; >> + chip->owner = THIS_MODULE; >> + chip->base = 0; >> + chip->can_sleep = 0; >> + chip->ngpio = 20; >> + chip->direction_input = octeon_gpio_dir_in; >> + chip->get = octeon_gpio_get; >> + chip->direction_output = octeon_gpio_dir_out; >> + chip->set = octeon_gpio_set; >> + err = gpiochip_add(chip); >> + if (err) >> + goto out; >> + >> + dev_info(&pdev->dev, "OCTEON GPIO\n"); > > This is like shouting "REAL MADRID!" in the bootlog, be a bit more > precise: "octeon GPIO driver probed\n" or something so we know what > is happening. No, more akin to 'Real Madrid', as 'OCTEON' is the correct spelling of its given name. I will happily add "driver probed", and grudgingly switch to lower case if it is a necessary condition of patch acceptance. David Daney -- 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/