Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755580AbbGFT3c (ORCPT ); Mon, 6 Jul 2015 15:29:32 -0400 Received: from mail-pd0-f176.google.com ([209.85.192.176]:36787 "EHLO mail-pd0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755180AbbGFT2J (ORCPT ); Mon, 6 Jul 2015 15:28:09 -0400 From: Vaibhav Hiremath To: linux-i2c@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org, wsa@the-dreams.de, robert.jarzmik@free.fr, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, robh+dt@kernel.org, Yi Zhang , Vaibhav Hiremath Subject: [PATCH-v3 07/11] i2c: pxa: enable/disable i2c module across msg xfer Date: Tue, 7 Jul 2015 00:54:51 +0530 Message-Id: <1436210695-19159-8-git-send-email-vaibhav.hiremath@linaro.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1436210695-19159-1-git-send-email-vaibhav.hiremath@linaro.org> References: <1436210695-19159-1-git-send-email-vaibhav.hiremath@linaro.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4183 Lines: 138 From: Yi Zhang Enable i2c module/unit before transmission and disable when it finishes. why? It's because the i2c bus may be distrubed if the slave device, typically a touch, powers on. As we do not want to break slave mode support, this patch introduces DT property to control disable of the I2C module after xfer in master mode of operation. i2c-disable-after-xfer : If set, driver will disable I2C module after msg xfer Signed-off-by: Yi Zhang Signed-off-by: Vaibhav Hiremath --- drivers/i2c/busses/i2c-pxa.c | 43 +++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 41 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c index 2de9300..dfd1dd0 100644 --- a/drivers/i2c/busses/i2c-pxa.c +++ b/drivers/i2c/busses/i2c-pxa.c @@ -161,6 +161,7 @@ struct pxa_i2c { unsigned char master_code; unsigned long rate; bool highmode_enter; + bool disable_after_xfer; }; #define _IBMR(i2c) ((i2c)->reg_ibmr) @@ -284,6 +285,24 @@ static void i2c_pxa_scream_blue_murder(struct pxa_i2c *i2c, const char *why) static void i2c_pxa_master_complete(struct pxa_i2c *i2c, int ret); static irqreturn_t i2c_pxa_handler(int this_irq, void *dev_id); +/* enable/disable i2c unit */ +static inline int i2c_pxa_is_enabled(struct pxa_i2c *i2c) +{ + return (readl(_ICR(i2c)) & ICR_IUE); +} + +static inline void i2c_pxa_enable(struct pxa_i2c *i2c, bool enable) +{ + if (enable) { + if (!i2c_pxa_is_enabled(i2c)) { + writel(readl(_ICR(i2c)) | ICR_IUE, _ICR(i2c)); + udelay(100); + } + } else { + writel(readl(_ICR(i2c)) & ~ICR_IUE, _ICR(i2c)); + } +} + static inline int i2c_pxa_is_slavemode(struct pxa_i2c *i2c) { return !(readl(_ICR(i2c)) & ICR_SCLE); @@ -480,8 +499,7 @@ static void i2c_pxa_reset(struct pxa_i2c *i2c) i2c_pxa_set_slave(i2c, 0); /* enable unit */ - writel(readl(_ICR(i2c)) | ICR_IUE, _ICR(i2c)); - udelay(100); + i2c_pxa_enable(i2c, true); } @@ -832,6 +850,9 @@ static int i2c_pxa_pio_xfer(struct i2c_adapter *adap, struct pxa_i2c *i2c = adap->algo_data; int ret, i; + /* Enable i2c unit */ + i2c_pxa_enable(i2c, true); + /* If the I2C controller is disabled we need to reset it (probably due to a suspend/resume destroying state). We do this here as we can then avoid worrying about resuming the @@ -852,6 +873,11 @@ static int i2c_pxa_pio_xfer(struct i2c_adapter *adap, ret = -EREMOTEIO; out: i2c_pxa_set_slave(i2c, ret); + + /* disable i2c unit */ + if (i2c->disable_after_xfer) + i2c_pxa_enable(i2c, false); + return ret; } @@ -1067,6 +1093,9 @@ static int i2c_pxa_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num struct pxa_i2c *i2c = adap->algo_data; int ret, i; + /* Enable i2c unit */ + i2c_pxa_enable(i2c, true); + for (i = adap->retries; i >= 0; i--) { ret = i2c_pxa_do_xfer(i2c, msgs, num); if (ret != I2C_RETRY) @@ -1080,6 +1109,10 @@ static int i2c_pxa_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num ret = -EREMOTEIO; out: i2c_pxa_set_slave(i2c, ret); + /* disable i2c unit */ + if (i2c->disable_after_xfer) + i2c_pxa_enable(i2c, false); + return ret; } @@ -1120,6 +1153,9 @@ static int i2c_pxa_probe_dt(struct platform_device *pdev, struct pxa_i2c *i2c, /* For device tree we always use the dynamic or alias-assigned ID */ i2c->adap.nr = -1; + i2c->disable_after_xfer = of_property_read_bool(np, + "i2c-disable-after-xfer"); + if (of_get_property(np, "mrvl,i2c-polling", NULL)) i2c->use_pio = 1; if (of_get_property(np, "mrvl,i2c-fast-mode", NULL)) @@ -1271,6 +1307,9 @@ static int i2c_pxa_probe(struct platform_device *dev) platform_set_drvdata(dev, i2c); + if (i2c->disable_after_xfer) + i2c_pxa_enable(i2c, false); + #ifdef CONFIG_I2C_PXA_SLAVE dev_info(&i2c->adap.dev, " PXA I2C adapter, slave address %d\n", i2c->slave_addr); -- 1.9.1 -- 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/