From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-lf0-x22a.google.com ([2a00:1450:4010:c07::22a]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Zz2Lf-0003hL-Qh for barebox@lists.infradead.org; Wed, 18 Nov 2015 13:00:33 +0000 Received: by lfs39 with SMTP id 39so25734433lfs.3 for ; Wed, 18 Nov 2015 05:00:09 -0800 (PST) From: Antony Pavlov Date: Wed, 18 Nov 2015 16:00:03 +0300 Message-Id: <1447851604-18072-2-git-send-email-antonynpavlov@gmail.com> In-Reply-To: <1447851604-18072-1-git-send-email-antonynpavlov@gmail.com> References: <1447851604-18072-1-git-send-email-antonynpavlov@gmail.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: [RFC 1/2] i2c: import multiplexed I2C bus core support from linux kernel To: barebox@lists.infradead.org Signed-off-by: Antony Pavlov --- drivers/i2c/Kconfig | 7 +++ drivers/i2c/Makefile | 1 + drivers/i2c/i2c-mux.c | 118 ++++++++++++++++++++++++++++++++++++++++++++++++++ include/i2c/i2c-mux.h | 40 +++++++++++++++++ include/i2c/i2c.h | 6 ++- 5 files changed, 171 insertions(+), 1 deletion(-) diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig index 0c6aec3..21cf0ec 100644 --- a/drivers/i2c/Kconfig +++ b/drivers/i2c/Kconfig @@ -6,4 +6,11 @@ if I2C source drivers/i2c/algos/Kconfig source drivers/i2c/busses/Kconfig +config I2C_MUX + tristate "I2C bus multiplexing support" + help + Say Y here if you want the I2C core to support the ability to + handle multiplexed I2C bus topologies, by presenting each + multiplexed segment as a I2C adapter. + endif diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile index 648d844..5ce0d0a 100644 --- a/drivers/i2c/Makefile +++ b/drivers/i2c/Makefile @@ -1 +1,2 @@ obj-$(CONFIG_I2C) += i2c.o i2c-smbus.o busses/ algos/ +obj-$(CONFIG_I2C_MUX) += i2c-mux.o diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c new file mode 100644 index 0000000..8c4952a --- /dev/null +++ b/drivers/i2c/i2c-mux.c @@ -0,0 +1,118 @@ +#include +#include +#include +#include +#include +#include + +/* multiplexer per channel data */ +struct i2c_mux_priv { + struct i2c_adapter adap; + + struct i2c_adapter *parent; + struct device_d *mux_dev; + void *mux_priv; + u32 chan_id; + + int (*select)(struct i2c_adapter *, void *mux_priv, u32 chan_id); + int (*deselect)(struct i2c_adapter *, void *mux_priv, u32 chan_id); +}; + +static int i2c_mux_master_xfer(struct i2c_adapter *adap, + struct i2c_msg msgs[], int num) +{ + struct i2c_mux_priv *priv = adap->algo_data; + struct i2c_adapter *parent = priv->parent; + int ret; + + /* Switch to the right mux port and perform the transfer. */ + + ret = priv->select(parent, priv->mux_priv, priv->chan_id); + if (ret >= 0) + ret = parent->master_xfer(parent, msgs, num); + if (priv->deselect) + priv->deselect(parent, priv->mux_priv, priv->chan_id); + + return ret; +} + +struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent, + struct device_d *mux_dev, + void *mux_priv, u32 force_nr, u32 chan_id, + int (*select) (struct i2c_adapter *, + void *, u32), + int (*deselect) (struct i2c_adapter *, + void *, u32)) +{ + struct i2c_mux_priv *priv; + int ret; + + priv = kzalloc(sizeof(struct i2c_mux_priv), GFP_KERNEL); + if (!priv) + return NULL; + + /* Set up private adapter data */ + priv->parent = parent; + priv->mux_dev = mux_dev; + priv->mux_priv = mux_priv; + priv->chan_id = chan_id; + priv->select = select; + priv->deselect = deselect; + + /* Need to do algo dynamically because we don't know ahead + * of time what sort of physical adapter we'll be dealing with. + */ + if (parent->master_xfer) + priv->adap.master_xfer = i2c_mux_master_xfer; + + /* Now fill out new adapter structure */ + priv->adap.algo_data = priv; + priv->adap.dev.parent = &parent->dev; + priv->adap.retries = parent->retries; + + /* + * Try to populate the mux adapter's device_node, expands to + * nothing if !CONFIG_OF. + */ + if (mux_dev->device_node) { + struct device_node *child; + u32 reg; + + for_each_child_of_node(mux_dev->device_node, child) { + ret = of_property_read_u32(child, "reg", ®); + if (ret) + continue; + if (chan_id == reg) { + priv->adap.dev.device_node = child; + break; + } + } + } + + /* FIXME */ +// priv->adap.nr = mux_dev->id; + priv->adap.nr = -1; + ret = i2c_add_numbered_adapter(&priv->adap); + + if (ret < 0) { + dev_err(&parent->dev, + "failed to add mux-adapter (error=%d)\n", + ret); + kfree(priv); + return NULL; + } + + dev_info(&parent->dev, "Added multiplexed i2c bus %d\n", + i2c_adapter_id(&priv->adap)); + + return &priv->adap; +} +EXPORT_SYMBOL_GPL(i2c_add_mux_adapter); + +void i2c_del_mux_adapter(struct i2c_adapter *adap) +{ + struct i2c_mux_priv *priv = adap->algo_data; + + free(priv); +} +EXPORT_SYMBOL_GPL(i2c_del_mux_adapter); diff --git a/include/i2c/i2c-mux.h b/include/i2c/i2c-mux.h new file mode 100644 index 0000000..8022399 --- /dev/null +++ b/include/i2c/i2c-mux.h @@ -0,0 +1,40 @@ +/* + * + * i2c-mux.h - functions for the i2c-bus mux support + * + * Copyright (c) 2008-2009 Rodolfo Giometti + * Copyright (c) 2008-2009 Eurotech S.p.A. + * Michael Lawnick + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * 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. + * + */ + +#ifndef _LINUX_I2C_MUX_H +#define _LINUX_I2C_MUX_H + +/* + * Called to create a i2c bus on a multiplexed bus segment. + * The mux_dev and chan_id parameters are passed to the select + * and deselect callback functions to perform hardware-specific + * mux control. + */ +struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent, + struct device_d *mux_dev, + void *mux_priv, u32 force_nr, u32 chan_id, + int (*select) (struct i2c_adapter *, + void *mux_dev, u32 chan_id), + int (*deselect) (struct i2c_adapter *, + void *mux_dev, u32 chan_id)); + +void i2c_del_mux_adapter(struct i2c_adapter *adap); + +#endif /* _LINUX_I2C_MUX_H */ diff --git a/include/i2c/i2c.h b/include/i2c/i2c.h index 3fab76d9..8f7aae9 100644 --- a/include/i2c/i2c.h +++ b/include/i2c/i2c.h @@ -245,7 +245,11 @@ extern struct list_head i2c_adapter_list; extern struct i2c_client * i2c_new_dummy(struct i2c_adapter *adap, u16 address); - +/* Return the adapter number for a specific adapter */ +static inline int i2c_adapter_id(struct i2c_adapter *adap) +{ + return adap->nr; +} extern int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num); extern int i2c_master_send(struct i2c_client *client, const char *buf, int count); -- 2.6.2 _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox