From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ryan Mallon Subject: Re: [PATCH v6 08/12] gpio: add ti-ssp gpio driver Date: Mon, 22 Nov 2010 09:02:45 +1300 Message-ID: <4CE97AE5.3040801@bluewatersys.com> References: <1290182156-20104-1-git-send-email-cyril@ti.com> <1290182156-20104-9-git-send-email-cyril@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: davinci-linux-open-source-VycZQUHpC/PFrsHnngEfi1aTQe2KTcn/@public.gmane.org, dbrownell-Rn4VEauK+AKRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, sameo-VuQAYsv1563Yd54FQh9/CA@public.gmane.org, khilman-1D3HCaltpLuhEniVeURVKkEOCMrvLtNR@public.gmane.org, broonie-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org, rpurdie-Fm38FmjxZ/leoWH0uzbU5w@public.gmane.org, alan-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org, spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, lrg-kDsPt+C1G03kYMGBc/C6ZA@public.gmane.org To: Cyril Chemparathy Return-path: In-Reply-To: <1290182156-20104-9-git-send-email-cyril-l0cyMroinI0@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: spi-devel-general-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-spi.vger.kernel.org On 11/20/2010 04:55 AM, Cyril Chemparathy wrote: > TI's SSP controller pins can be directly read and written to behave like a > GPIO. This patch adds a GPIO driver that exposes such functionality. > > Signed-off-by: Cyril Chemparathy > --- > +static int __devinit ti_ssp_gpio_probe(struct platform_device *pdev) > +{ > + const struct ti_ssp_gpio_data *pdata = pdev->dev.platform_data; > + struct device *dev = &pdev->dev; > + struct ti_ssp_gpio_chip *gpio; > + int error; > + > + if (!pdata) { > + dev_err(dev, "platform data not found\n"); > + return -EINVAL; > + } > + > + gpio = kzalloc(sizeof(*gpio), GFP_KERNEL); > + if (!gpio) { > + dev_err(dev, "cannot allocate driver data\n"); > + return -ENOMEM; > + } > + > + gpio->dev = dev; > + gpio->iosel = SSP_PIN_SEL(0, SSP_IN) | SSP_PIN_SEL(1, SSP_IN) | > + SSP_PIN_SEL(2, SSP_IN) | SSP_PIN_SEL(3, SSP_IN); > + error = ti_ssp_set_iosel(gpio->dev, gpio->iosel); > + if (error < 0) { > + dev_err(dev, "gpio io setup failed (%d)\n", error); > + goto error; > + } > + > + spin_lock_init(&gpio->lock); > + platform_set_drvdata(pdev, gpio); This looks wrong. gpio is of type ti_ssp_gpio_chip, but the ssp core functions, ssp_read, etc, use dev_to_ssp: static inline struct ti_ssp *dev_to_ssp(struct device *dev) { return dev_get_drvdata(dev->parent); } If I understand correctly, the ssp core can only be used to for one peripheral at a time. Currently the code will allow you to install several peripherals at once, which will lead to odd behaviour at runtime. Maybe a better approach would be to have something like this in drivers/mfd/ti-ssp.c: struct ti_ssp { struct resource *res; struct device *dev; void __iomem *regs; struct clk *clk; int irq; wait_queue_head_t wqh; int in_use; }; static struct ti_ssp ti_ssp = { .in_use = 0, }; static DEFINE_SPINLOCK(ti_ssp_lock); struct ti_ssp *ti_ssp_get(void) { spin_lock(&ti_ssp_lock); if (ti_ssp.in_use) { spin_unlock(&ti_ssp_lock); return NULL; } ti_ssp.in_use = 1; spin_unlock(&ti_ssp_lock); return &ti_ssp; } int ti_ssp_put(void) { spin_lock(&ti_ssp_lock); if (!ti_ssp.in_use) { spin_unlock(&ti_ssp_lock); return -ENODEV; } ti_ssp.in_use = 0; spin_unlock(&ti_ssp_lock); return 0; } This way, the ssp core api functions can take struct ti_ssp * as their first argument (which can still be an opaque pointer) and the code protects against multiple peripherals attempting to register the ssp core. ~Ryan -- Bluewater Systems Ltd - ARM Technology Solution Centre Ryan Mallon 5 Amuri Park, 404 Barbadoes St ryan-7Wk5F4Od5/oYd5yxfr4S2w@public.gmane.org PO Box 13 889, Christchurch 8013 http://www.bluewatersys.com New Zealand Phone: +64 3 3779127 Freecall: Australia 1800 148 751 Fax: +64 3 3779135 USA 1800 261 2934 ------------------------------------------------------------------------------ Beautiful is writing same markup. Internet Explorer 9 supports standards for HTML5, CSS3, SVG 1.1, ECMAScript5, and DOM L2 & L3. Spend less time writing and rewriting code and more time creating great experiences on the web. Be a part of the beta today http://p.sf.net/sfu/msIE9-sfdev2dev