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author | Wolfram Sang <w.sang@pengutronix.de> | 2012-04-25 22:29:43 +0200 |
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committer | Wolfram Sang <w.sang@pengutronix.de> | 2012-05-12 14:28:17 +0200 |
commit | b4f0b74ea37789eeeabe57b7ccd5808df076c081 (patch) | |
tree | 215c7bff20b134f23886456fcf9f8421ca902196 /drivers/i2c/muxes/pca9541.c | |
parent | 0938643e533cc80ef0cdfdd2e260c4910d0f8bc7 (diff) | |
download | linux-3.10-b4f0b74ea37789eeeabe57b7ccd5808df076c081.tar.gz linux-3.10-b4f0b74ea37789eeeabe57b7ccd5808df076c081.tar.bz2 linux-3.10-b4f0b74ea37789eeeabe57b7ccd5808df076c081.zip |
i2c: muxes: rename first set of drivers to a standard pattern
Apply a naming pattern like in the rest of the subsystem to a first set
of mux drivers. Those drivers are the low-hanging fruit; we want to pick
them to motivate upcoming drivers to follow the new pattern. The missing
GPIO driver will be converted in a later patch.
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Acked-by: Guenter Roeck <guenter.roeck@ericsson.com> (pca9541)
Acked-by: Jean Delvare <khali@linux-fr.org>
Diffstat (limited to 'drivers/i2c/muxes/pca9541.c')
-rw-r--r-- | drivers/i2c/muxes/pca9541.c | 401 |
1 files changed, 0 insertions, 401 deletions
diff --git a/drivers/i2c/muxes/pca9541.c b/drivers/i2c/muxes/pca9541.c deleted file mode 100644 index 8aacde1516a..00000000000 --- a/drivers/i2c/muxes/pca9541.c +++ /dev/null @@ -1,401 +0,0 @@ -/* - * I2C multiplexer driver for PCA9541 bus master selector - * - * Copyright (c) 2010 Ericsson AB. - * - * Author: Guenter Roeck <guenter.roeck@ericsson.com> - * - * Derived from: - * pca954x.c - * - * Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it> - * Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it> - * - * This file is licensed under the terms of the GNU General Public - * License version 2. This program is licensed "as is" without any - * warranty of any kind, whether express or implied. - */ - -#include <linux/module.h> -#include <linux/init.h> -#include <linux/jiffies.h> -#include <linux/delay.h> -#include <linux/slab.h> -#include <linux/device.h> -#include <linux/i2c.h> -#include <linux/i2c-mux.h> - -#include <linux/i2c/pca954x.h> - -/* - * The PCA9541 is a bus master selector. It supports two I2C masters connected - * to a single slave bus. - * - * Before each bus transaction, a master has to acquire bus ownership. After the - * transaction is complete, bus ownership has to be released. This fits well - * into the I2C multiplexer framework, which provides select and release - * functions for this purpose. For this reason, this driver is modeled as - * single-channel I2C bus multiplexer. - * - * This driver assumes that the two bus masters are controlled by two different - * hosts. If a single host controls both masters, platform code has to ensure - * that only one of the masters is instantiated at any given time. - */ - -#define PCA9541_CONTROL 0x01 -#define PCA9541_ISTAT 0x02 - -#define PCA9541_CTL_MYBUS (1 << 0) -#define PCA9541_CTL_NMYBUS (1 << 1) -#define PCA9541_CTL_BUSON (1 << 2) -#define PCA9541_CTL_NBUSON (1 << 3) -#define PCA9541_CTL_BUSINIT (1 << 4) -#define PCA9541_CTL_TESTON (1 << 6) -#define PCA9541_CTL_NTESTON (1 << 7) - -#define PCA9541_ISTAT_INTIN (1 << 0) -#define PCA9541_ISTAT_BUSINIT (1 << 1) -#define PCA9541_ISTAT_BUSOK (1 << 2) -#define PCA9541_ISTAT_BUSLOST (1 << 3) -#define PCA9541_ISTAT_MYTEST (1 << 6) -#define PCA9541_ISTAT_NMYTEST (1 << 7) - -#define BUSON (PCA9541_CTL_BUSON | PCA9541_CTL_NBUSON) -#define MYBUS (PCA9541_CTL_MYBUS | PCA9541_CTL_NMYBUS) -#define mybus(x) (!((x) & MYBUS) || ((x) & MYBUS) == MYBUS) -#define busoff(x) (!((x) & BUSON) || ((x) & BUSON) == BUSON) - -/* arbitration timeouts, in jiffies */ -#define ARB_TIMEOUT (HZ / 8) /* 125 ms until forcing bus ownership */ -#define ARB2_TIMEOUT (HZ / 4) /* 250 ms until acquisition failure */ - -/* arbitration retry delays, in us */ -#define SELECT_DELAY_SHORT 50 -#define SELECT_DELAY_LONG 1000 - -struct pca9541 { - struct i2c_adapter *mux_adap; - unsigned long select_timeout; - unsigned long arb_timeout; -}; - -static const struct i2c_device_id pca9541_id[] = { - {"pca9541", 0}, - {} -}; - -MODULE_DEVICE_TABLE(i2c, pca9541_id); - -/* - * Write to chip register. Don't use i2c_transfer()/i2c_smbus_xfer() - * as they will try to lock the adapter a second time. - */ -static int pca9541_reg_write(struct i2c_client *client, u8 command, u8 val) -{ - struct i2c_adapter *adap = client->adapter; - int ret; - - if (adap->algo->master_xfer) { - struct i2c_msg msg; - char buf[2]; - - msg.addr = client->addr; - msg.flags = 0; - msg.len = 2; - buf[0] = command; - buf[1] = val; - msg.buf = buf; - ret = adap->algo->master_xfer(adap, &msg, 1); - } else { - union i2c_smbus_data data; - - data.byte = val; - ret = adap->algo->smbus_xfer(adap, client->addr, - client->flags, - I2C_SMBUS_WRITE, - command, - I2C_SMBUS_BYTE_DATA, &data); - } - - return ret; -} - -/* - * Read from chip register. Don't use i2c_transfer()/i2c_smbus_xfer() - * as they will try to lock adapter a second time. - */ -static int pca9541_reg_read(struct i2c_client *client, u8 command) -{ - struct i2c_adapter *adap = client->adapter; - int ret; - u8 val; - - if (adap->algo->master_xfer) { - struct i2c_msg msg[2] = { - { - .addr = client->addr, - .flags = 0, - .len = 1, - .buf = &command - }, - { - .addr = client->addr, - .flags = I2C_M_RD, - .len = 1, - .buf = &val - } - }; - ret = adap->algo->master_xfer(adap, msg, 2); - if (ret == 2) - ret = val; - else if (ret >= 0) - ret = -EIO; - } else { - union i2c_smbus_data data; - - ret = adap->algo->smbus_xfer(adap, client->addr, - client->flags, - I2C_SMBUS_READ, - command, - I2C_SMBUS_BYTE_DATA, &data); - if (!ret) - ret = data.byte; - } - return ret; -} - -/* - * Arbitration management functions - */ - -/* Release bus. Also reset NTESTON and BUSINIT if it was set. */ -static void pca9541_release_bus(struct i2c_client *client) -{ - int reg; - - reg = pca9541_reg_read(client, PCA9541_CONTROL); - if (reg >= 0 && !busoff(reg) && mybus(reg)) - pca9541_reg_write(client, PCA9541_CONTROL, - (reg & PCA9541_CTL_NBUSON) >> 1); -} - -/* - * Arbitration is defined as a two-step process. A bus master can only activate - * the slave bus if it owns it; otherwise it has to request ownership first. - * This multi-step process ensures that access contention is resolved - * gracefully. - * - * Bus Ownership Other master Action - * state requested access - * ---------------------------------------------------- - * off - yes wait for arbitration timeout or - * for other master to drop request - * off no no take ownership - * off yes no turn on bus - * on yes - done - * on no - wait for arbitration timeout or - * for other master to release bus - * - * The main contention point occurs if the slave bus is off and both masters - * request ownership at the same time. In this case, one master will turn on - * the slave bus, believing that it owns it. The other master will request - * bus ownership. Result is that the bus is turned on, and master which did - * _not_ own the slave bus before ends up owning it. - */ - -/* Control commands per PCA9541 datasheet */ -static const u8 pca9541_control[16] = { - 4, 0, 1, 5, 4, 4, 5, 5, 0, 0, 1, 1, 0, 4, 5, 1 -}; - -/* - * Channel arbitration - * - * Return values: - * <0: error - * 0 : bus not acquired - * 1 : bus acquired - */ -static int pca9541_arbitrate(struct i2c_client *client) -{ - struct pca9541 *data = i2c_get_clientdata(client); - int reg; - - reg = pca9541_reg_read(client, PCA9541_CONTROL); - if (reg < 0) - return reg; - - if (busoff(reg)) { - int istat; - /* - * Bus is off. Request ownership or turn it on unless - * other master requested ownership. - */ - istat = pca9541_reg_read(client, PCA9541_ISTAT); - if (!(istat & PCA9541_ISTAT_NMYTEST) - || time_is_before_eq_jiffies(data->arb_timeout)) { - /* - * Other master did not request ownership, - * or arbitration timeout expired. Take the bus. - */ - pca9541_reg_write(client, - PCA9541_CONTROL, - pca9541_control[reg & 0x0f] - | PCA9541_CTL_NTESTON); - data->select_timeout = SELECT_DELAY_SHORT; - } else { - /* - * Other master requested ownership. - * Set extra long timeout to give it time to acquire it. - */ - data->select_timeout = SELECT_DELAY_LONG * 2; - } - } else if (mybus(reg)) { - /* - * Bus is on, and we own it. We are done with acquisition. - * Reset NTESTON and BUSINIT, then return success. - */ - if (reg & (PCA9541_CTL_NTESTON | PCA9541_CTL_BUSINIT)) - pca9541_reg_write(client, - PCA9541_CONTROL, - reg & ~(PCA9541_CTL_NTESTON - | PCA9541_CTL_BUSINIT)); - return 1; - } else { - /* - * Other master owns the bus. - * If arbitration timeout has expired, force ownership. - * Otherwise request it. - */ - data->select_timeout = SELECT_DELAY_LONG; - if (time_is_before_eq_jiffies(data->arb_timeout)) { - /* Time is up, take the bus and reset it. */ - pca9541_reg_write(client, - PCA9541_CONTROL, - pca9541_control[reg & 0x0f] - | PCA9541_CTL_BUSINIT - | PCA9541_CTL_NTESTON); - } else { - /* Request bus ownership if needed */ - if (!(reg & PCA9541_CTL_NTESTON)) - pca9541_reg_write(client, - PCA9541_CONTROL, - reg | PCA9541_CTL_NTESTON); - } - } - return 0; -} - -static int pca9541_select_chan(struct i2c_adapter *adap, void *client, u32 chan) -{ - struct pca9541 *data = i2c_get_clientdata(client); - int ret; - unsigned long timeout = jiffies + ARB2_TIMEOUT; - /* give up after this time */ - - data->arb_timeout = jiffies + ARB_TIMEOUT; - /* force bus ownership after this time */ - - do { - ret = pca9541_arbitrate(client); - if (ret) - return ret < 0 ? ret : 0; - - if (data->select_timeout == SELECT_DELAY_SHORT) - udelay(data->select_timeout); - else - msleep(data->select_timeout / 1000); - } while (time_is_after_eq_jiffies(timeout)); - - return -ETIMEDOUT; -} - -static int pca9541_release_chan(struct i2c_adapter *adap, - void *client, u32 chan) -{ - pca9541_release_bus(client); - return 0; -} - -/* - * I2C init/probing/exit functions - */ -static int pca9541_probe(struct i2c_client *client, - const struct i2c_device_id *id) -{ - struct i2c_adapter *adap = client->adapter; - struct pca954x_platform_data *pdata = client->dev.platform_data; - struct pca9541 *data; - int force; - int ret = -ENODEV; - - if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE_DATA)) - goto err; - - data = kzalloc(sizeof(struct pca9541), GFP_KERNEL); - if (!data) { - ret = -ENOMEM; - goto err; - } - - i2c_set_clientdata(client, data); - - /* - * I2C accesses are unprotected here. - * We have to lock the adapter before releasing the bus. - */ - i2c_lock_adapter(adap); - pca9541_release_bus(client); - i2c_unlock_adapter(adap); - - /* Create mux adapter */ - - force = 0; - if (pdata) - force = pdata->modes[0].adap_id; - data->mux_adap = i2c_add_mux_adapter(adap, &client->dev, client, - force, 0, - pca9541_select_chan, - pca9541_release_chan); - - if (data->mux_adap == NULL) { - dev_err(&client->dev, "failed to register master selector\n"); - goto exit_free; - } - - dev_info(&client->dev, "registered master selector for I2C %s\n", - client->name); - - return 0; - -exit_free: - kfree(data); -err: - return ret; -} - -static int pca9541_remove(struct i2c_client *client) -{ - struct pca9541 *data = i2c_get_clientdata(client); - - i2c_del_mux_adapter(data->mux_adap); - - kfree(data); - return 0; -} - -static struct i2c_driver pca9541_driver = { - .driver = { - .name = "pca9541", - .owner = THIS_MODULE, - }, - .probe = pca9541_probe, - .remove = pca9541_remove, - .id_table = pca9541_id, -}; - -module_i2c_driver(pca9541_driver); - -MODULE_AUTHOR("Guenter Roeck <guenter.roeck@ericsson.com>"); -MODULE_DESCRIPTION("PCA9541 I2C master selector driver"); -MODULE_LICENSE("GPL v2"); |