From patchwork Thu Jan 3 05:46:18 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stephen Warren X-Patchwork-Id: 1926251 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork1.kernel.org Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) by patchwork1.kernel.org (Postfix) with ESMTP id 8790C3FDDA for ; Thu, 3 Jan 2013 05:49:54 +0000 (UTC) Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1TqddO-0007ab-Mp; Thu, 03 Jan 2013 05:46:30 +0000 Received: from avon.wwwdotorg.org ([2001:470:1f0f:bd7::2]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1TqddJ-0007aG-OM; Thu, 03 Jan 2013 05:46:26 +0000 Received: from severn.wwwdotorg.org (unknown [192.168.65.5]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by avon.wwwdotorg.org (Postfix) with ESMTPS id 0E83612E4CC; Wed, 2 Jan 2013 22:47:20 -0700 (MST) Received: from dart.wwwdotorg.org (c-24-9-124-73.hsd1.co.comcast.net [24.9.124.73]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by severn.wwwdotorg.org (Postfix) with ESMTPSA id E8E55E461A; Wed, 2 Jan 2013 22:46:23 -0700 (MST) From: Stephen Warren To: Wolfram Sang , Ben Dooks Subject: [PATCH] i2c: add bcm2835 driver Date: Wed, 2 Jan 2013 22:46:18 -0700 Message-Id: <1357191978-11038-1-git-send-email-swarren@wwwdotorg.org> X-Mailer: git-send-email 1.7.10.4 X-NVConfidentiality: public X-Virus-Scanned: clamav-milter 0.96.5 at avon.wwwdotorg.org X-Virus-Status: Clean X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20130103_004625_983844_20410EB5 X-CRM114-Status: GOOD ( 21.68 ) X-Spam-Score: -2.6 (--) X-Spam-Report: SpamAssassin version 3.3.2 on merlin.infradead.org summary: Content analysis details: (-2.6 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 SPF_PASS SPF: sender matches SPF record -0.7 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Cc: Stephen Warren , devicetree-discuss@lists.ozlabs.org, Rob Herring , Grant Likely , linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-i2c@vger.kernel.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org This implements a very basic I2C host driver for the BCM2835 SoC. Missing features so far are: * Clock rate adjustment. * 10-bit addressing. * DMA. Signed-off-by: Stephen Warren Reviewed-by: Grant Likely --- .../devicetree/bindings/i2c/brcm,bcm2835-i2c.txt | 20 ++ drivers/i2c/busses/Kconfig | 12 + drivers/i2c/busses/Makefile | 1 + drivers/i2c/busses/i2c-bcm2835.c | 331 ++++++++++++++++++++ 4 files changed, 364 insertions(+) create mode 100644 Documentation/devicetree/bindings/i2c/brcm,bcm2835-i2c.txt create mode 100644 drivers/i2c/busses/i2c-bcm2835.c diff --git a/Documentation/devicetree/bindings/i2c/brcm,bcm2835-i2c.txt b/Documentation/devicetree/bindings/i2c/brcm,bcm2835-i2c.txt new file mode 100644 index 0000000..e9de375 --- /dev/null +++ b/Documentation/devicetree/bindings/i2c/brcm,bcm2835-i2c.txt @@ -0,0 +1,20 @@ +Broadcom BCM2835 I2C controller + +Required properties: +- compatible : Should be "brcm,bcm2835-i2c". +- reg: Should contain register location and length. +- interrupts: Should contain interrupt. +- clocks : The clock feeding the I2C controller. + +Recommended properties: +- clock-frequency : desired I2C bus clock frequency in Hz. + +Example: + +i2c@20205000 { + compatible = "brcm,bcm2835-i2c"; + reg = <0x7e205000 0x1000>; + interrupts = <2 21>; + clocks = <&clk_i2c>; + clock-frequency = <100000>; +}; diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig index bdca511..5aab774 100644 --- a/drivers/i2c/busses/Kconfig +++ b/drivers/i2c/busses/Kconfig @@ -319,6 +319,18 @@ config I2C_AU1550 This driver can also be built as a module. If so, the module will be called i2c-au1550. +config I2C_BCM2835 + tristate "Broadcom BCM2835 I2C controller" + depends on ARCH_BCM2835 + help + If you say yes to this option, support will be included for the + BCM2835 I2C controller. + + If you don't know what to do here, say N. + + This support is also available as a module. If so, the module + will be called i2c-bcm2835. + config I2C_BLACKFIN_TWI tristate "Blackfin TWI I2C support" depends on BLACKFIN diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile index 6181f3f..a52a891 100644 --- a/drivers/i2c/busses/Makefile +++ b/drivers/i2c/busses/Makefile @@ -30,6 +30,7 @@ obj-$(CONFIG_I2C_POWERMAC) += i2c-powermac.o # Embedded system I2C/SMBus host controller drivers obj-$(CONFIG_I2C_AT91) += i2c-at91.o obj-$(CONFIG_I2C_AU1550) += i2c-au1550.o +obj-$(CONFIG_I2C_BCM2835) += i2c-bcm2835.o obj-$(CONFIG_I2C_BLACKFIN_TWI) += i2c-bfin-twi.o obj-$(CONFIG_I2C_CBUS_GPIO) += i2c-cbus-gpio.o obj-$(CONFIG_I2C_CPM) += i2c-cpm.o diff --git a/drivers/i2c/busses/i2c-bcm2835.c b/drivers/i2c/busses/i2c-bcm2835.c new file mode 100644 index 0000000..c212471 --- /dev/null +++ b/drivers/i2c/busses/i2c-bcm2835.c @@ -0,0 +1,331 @@ +/* + * BCM2835 master mode driver + * + * This software is licensed under the terms of the GNU General Public + * License version 2, as published by the Free Software Foundation, and + * may be copied, distributed, and modified under those terms. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define BCM2835_I2C_C 0x0 +#define BCM2835_I2C_S 0x4 +#define BCM2835_I2C_DLEN 0x8 +#define BCM2835_I2C_A 0xc +#define BCM2835_I2C_FIFO 0x10 +#define BCM2835_I2C_DIV 0x14 +#define BCM2835_I2C_DEL 0x18 +#define BCM2835_I2C_CLKT 0x1c + +#define BCM2835_I2C_C_READ BIT(0) +#define BCM2835_I2C_C_CLEAR BIT(4) /* bits 4 and 5 both clear */ +#define BCM2835_I2C_C_ST BIT(7) +#define BCM2835_I2C_C_INTD BIT(8) +#define BCM2835_I2C_C_INTT BIT(9) +#define BCM2835_I2C_C_INTR BIT(10) +#define BCM2835_I2C_C_I2CEN BIT(15) + +#define BCM2835_I2C_S_TA BIT(0) +#define BCM2835_I2C_S_DONE BIT(1) +#define BCM2835_I2C_S_TXW BIT(2) +#define BCM2835_I2C_S_RXR BIT(3) +#define BCM2835_I2C_S_TXD BIT(4) +#define BCM2835_I2C_S_RXD BIT(5) +#define BCM2835_I2C_S_TXE BIT(6) +#define BCM2835_I2C_S_RXF BIT(7) +#define BCM2835_I2C_S_ERR BIT(8) +#define BCM2835_I2C_S_CLKT BIT(9) +#define BCM2835_I2C_S_LEN BIT(10) /* Fake bit for SW error reporting */ + +#define BCM2835_I2C_TIMEOUT (msecs_to_jiffies(1000)) + +struct bcm2835_i2c_dev { + struct device *dev; + void __iomem *regs; + struct i2c_adapter adapter; + struct completion completion; + u32 msg_err; + u8 *msg_buf; + size_t msg_buf_remaining; +}; + +static inline void bcm2835_i2c_writel(struct bcm2835_i2c_dev *i2c_dev, + u32 reg, u32 val) +{ + writel(val, i2c_dev->regs + reg); +} + +static inline u32 bcm2835_i2c_readl(struct bcm2835_i2c_dev *i2c_dev, u32 reg) +{ + return readl(i2c_dev->regs + reg); +} + +static void bcm2835_fill_txfifo(struct bcm2835_i2c_dev *i2c_dev) +{ + u32 val; + + for (;;) { + if (!i2c_dev->msg_buf_remaining) + return; + val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S); + if (!(val & BCM2835_I2C_S_TXD)) + break; + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_FIFO, + *i2c_dev->msg_buf); + i2c_dev->msg_buf++; + i2c_dev->msg_buf_remaining--; + } +} + +static void bcm2835_drain_rxfifo(struct bcm2835_i2c_dev *i2c_dev) +{ + u32 val; + + for (;;) { + if (!i2c_dev->msg_buf_remaining) + return; + val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S); + if (!(val & BCM2835_I2C_S_RXD)) + break; + *i2c_dev->msg_buf = bcm2835_i2c_readl(i2c_dev, + BCM2835_I2C_FIFO); + i2c_dev->msg_buf++; + i2c_dev->msg_buf_remaining--; + } +} + +static irqreturn_t bcm2835_i2c_isr(int this_irq, void *data) +{ + struct bcm2835_i2c_dev *i2c_dev = data; + u32 val, err; + + val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S); + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_S, val); + + err = val & (BCM2835_I2C_S_CLKT | BCM2835_I2C_S_ERR); + if (err) { + i2c_dev->msg_err = err; + complete(&i2c_dev->completion); + return IRQ_HANDLED; + } + + if (val & BCM2835_I2C_S_RXD) { + bcm2835_drain_rxfifo(i2c_dev); + if (!(val & BCM2835_I2C_S_DONE)) + return IRQ_HANDLED; + } + + if (val & BCM2835_I2C_S_DONE) { + if (i2c_dev->msg_buf_remaining) + i2c_dev->msg_err = BCM2835_I2C_S_LEN; + else + i2c_dev->msg_err = 0; + complete(&i2c_dev->completion); + return IRQ_HANDLED; + } + + if (val & BCM2835_I2C_S_TXD) { + bcm2835_fill_txfifo(i2c_dev); + return IRQ_HANDLED; + } + + return IRQ_NONE; +} + +static int bcm2835_i2c_xfer_msg(struct bcm2835_i2c_dev *i2c_dev, + struct i2c_msg *msg) +{ + u32 c; + int ret; + + i2c_dev->msg_buf = msg->buf; + i2c_dev->msg_buf_remaining = msg->len; + INIT_COMPLETION(i2c_dev->completion); + + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, BCM2835_I2C_C_CLEAR); + + if (msg->flags & I2C_M_RD) { + c = BCM2835_I2C_C_READ | BCM2835_I2C_C_INTR; + } else { + c = BCM2835_I2C_C_INTT; + bcm2835_fill_txfifo(i2c_dev); + } + c |= BCM2835_I2C_C_ST | BCM2835_I2C_C_INTD | BCM2835_I2C_C_I2CEN; + + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_A, msg->addr); + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DLEN, msg->len); + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, c); + + ret = wait_for_completion_timeout(&i2c_dev->completion, + BCM2835_I2C_TIMEOUT); + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, BCM2835_I2C_C_CLEAR); + if (WARN_ON(ret == 0)) { + dev_err(i2c_dev->dev, "i2c transfer timed out\n"); + return -ETIMEDOUT; + } + + if (likely(!i2c_dev->msg_err)) + return 0; + + if ((i2c_dev->msg_err & BCM2835_I2C_S_ERR) && + (msg->flags & I2C_M_IGNORE_NAK)) + return 0; + + dev_err(i2c_dev->dev, "i2c transfer failed: %x\n", i2c_dev->msg_err); + + if (i2c_dev->msg_err & BCM2835_I2C_S_ERR) + return -EREMOTEIO; + else + return -EIO; +} + +static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], + int num) +{ + struct bcm2835_i2c_dev *i2c_dev = i2c_get_adapdata(adap); + int i; + int ret = 0; + + for (i = 0; i < num; i++) { + ret = bcm2835_i2c_xfer_msg(i2c_dev, &msgs[i]); + if (ret) + break; + } + + return ret ?: i; +} + +static u32 bcm2835_i2c_func(struct i2c_adapter *adap) +{ + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; +} + +static const struct i2c_algorithm bcm2835_i2c_algo = { + .master_xfer = bcm2835_i2c_xfer, + .functionality = bcm2835_i2c_func, +}; + +static int __devinit bcm2835_i2c_probe(struct platform_device *pdev) +{ + struct bcm2835_i2c_dev *i2c_dev; + struct resource *mem, *requested, *irq; + int ret; + struct i2c_adapter *adap; + + i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL); + if (!i2c_dev) { + dev_err(&pdev->dev, "Cannot allocate i2c_dev\n"); + return -ENOMEM; + } + platform_set_drvdata(pdev, i2c_dev); + i2c_dev->dev = &pdev->dev; + init_completion(&i2c_dev->completion); + + mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (!mem) { + dev_err(&pdev->dev, "No mem resource\n"); + return -ENODEV; + } + + requested = devm_request_mem_region(&pdev->dev, mem->start, + resource_size(mem), + dev_name(&pdev->dev)); + if (!requested) { + dev_err(&pdev->dev, "Could not claim register region\n"); + return -EBUSY; + } + + i2c_dev->regs = devm_ioremap(&pdev->dev, mem->start, + resource_size(mem)); + if (!i2c_dev->regs) { + dev_err(&pdev->dev, "Could not map registers\n"); + return -ENOMEM; + } + + irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0); + if (!irq) { + dev_err(&pdev->dev, "No IRQ resource\n"); + return -ENODEV; + } + + ret = devm_request_irq(&pdev->dev, irq->start, bcm2835_i2c_isr, + IRQF_SHARED, dev_name(&pdev->dev), i2c_dev); + if (ret) { + dev_err(&pdev->dev, "Could not request IRQ\n"); + return -ENODEV; + } + + adap = &i2c_dev->adapter; + i2c_set_adapdata(adap, i2c_dev); + adap->owner = THIS_MODULE; + adap->class = I2C_CLASS_HWMON; + strlcpy(adap->name, "bcm2835 I2C adapter", sizeof(adap->name)); + adap->algo = &bcm2835_i2c_algo; + adap->dev.parent = &pdev->dev; + adap->nr = -1; + + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, 0); + + ret = i2c_add_numbered_adapter(adap); + if (ret) { + dev_err(&pdev->dev, "Could not add adapter\n"); + return ret; + } + + return 0; +} + +static int bcm2835_i2c_remove(struct platform_device *pdev) +{ + struct bcm2835_i2c_dev *i2c_dev = platform_get_drvdata(pdev); + + i2c_del_adapter(&i2c_dev->adapter); + + return 0; +} + +static const struct of_device_id bcm2835_i2c_of_match[] = { + { .compatible = "brcm,bcm2835-i2c" }, + {}, +}; +MODULE_DEVICE_TABLE(of, bcm2835_i2c_of_match); + +static struct platform_driver bcm2835_i2c_driver = { + .probe = bcm2835_i2c_probe, + .remove = bcm2835_i2c_remove, + .driver = { + .name = "i2c-bcm2835", + .owner = THIS_MODULE, + .of_match_table = bcm2835_i2c_of_match, + }, +}; + +static int __init bcm2835_i2c_init_driver(void) +{ + return platform_driver_register(&bcm2835_i2c_driver); +} +module_init(bcm2835_i2c_init_driver); + +static void __exit bcm2835_i2c_exit_driver(void) +{ + platform_driver_unregister(&bcm2835_i2c_driver); +} +module_exit(bcm2835_i2c_exit_driver); + +MODULE_AUTHOR("Stephen Warren "); +MODULE_DESCRIPTION("BCM2835 I2C bus adapter"); +MODULE_LICENSE("GPL v2"); +MODULE_ALIAS("platform:i2c-bcm2835");