Messages in this thread | | | Date | Fri, 31 Mar 2006 11:31:30 +0530 | From | Kaiwan N Billimoria <> | Subject | SPI <-> Parport (light) bridge code (Re: Stuck creating sysfs hooks for a driver..) |
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Jean Delvare wrote:
>Hi Kaiwan, > > > --snip--
>You must stay away from writing a driver for the board itself. What you >must write is in fact two different drivers: > >1* A driver for the SPI interface of your board (basically a parallel >port <-> SPI bridge). This driver will expose the device as an SPI bus >to the rest of the kernel. This driver doesn't care about what chip is >plugged on it. > > > Hi Jean,
1. Yes, i know, long time since the above message..yet i'm happy to say that i have built a (lightweight version) of the SPI<->parport bridge (file pasted below), which is based on your i2c-parport driver bridge code. It is built as a header file: the driver developer basically appends his/her adapter entry into the adapter_parm[] data structure and includes this file in the device driver.
>2* A driver for the LM70 temperature sensor chip, which doesn't care >about the chip location. This driver will use generic SPI commands as >offered by the spi kernel interface. > >This modular approach makes it possible to then reuse each of the >drivers. If you later have a similar board for a different chip, the >first driver will still work (assuming the new board uses SPI and the >same wiring conventions). If you later have an LM70 chip on a different >physical interface, the second driver will still work. > > > 2. I have also done this; i now have a working driver for a specific chip (the NS lm70CILD-3 eval board) based on the (above mentioned) SPi<->parport bridge. Basically, the "type 0" entry in the adapter_parm[] data structure is the lm70CILD-3 entry. The driver handles the other things, including creation of a sysfs hook (used to query the temperature from userspace).
>No, just do what every other hardware monitoring chip does, so that >support can be added for the lm70 chip in libsensors - then you win >instant support in all hardware monitoring application which rely on >libsensors, and even a few which do not. > >It's really not a matter of how many features a chip has. Look at the >lm75 or w83l785ts driver, you'll see they have very few features as >well. It's a matter of having a common standard for exporting the >values to user-space, so that the same library or application can >handle all sources with minimum effort. > >Thanks, > > 3. I still have to work on integrating the userspace conversion into libsensors (as recommended by yourself & others).
4. My intention at this point of time is for you (and others) to take a look at the spi-parport-light.h code and pl give me your feedback. I'm not posting a patch at this time..
5. Also, because it's a header, am not sure what approach to take when patching into the kernel; i mean, i can place it under the spi tree (either drivers/spi or include/linux/spi) but can't add the usual "obj-$(CONFIG_xxx) += xxx.o" line (as it's a header). Or can I do something like this?? i'm really quite uncertain, forgive me.. any suggestions on how i should go about this?
Thanks very much, Kaiwan.
PS> If you'd like to see a usage example, i can post the lm70CILD3.c driver code..
+++++++++++++++++++++ File spi-parport-light.h +++++++++++++++++++++++++++++++++++++++
--- /* ------------------------------------------------------------------------ * * spi-parport-light.h * * SPI bus over parallel port * * ------------------------------------------------------------------------ * Copyright (C) 2006 Kaiwan N Billimoria <kaiwan@designergraphix.com> Heavily based on i2c-parport-light.c Copyright (C) 2003-2004 Jean Delvare <khali@linux-fr.org> 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.
You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * ------------------------------------------------------------------------ */
#ifdef DATA #undef DATA #endif
#define DATA 0 #define STAT 1 #define CTRL 2
struct lineop { u8 val; u8 port; u8 inverted; };
struct adapter_parm { char *name; struct lineop setsda; struct lineop setscl; struct lineop setcsl; // chip select struct lineop getsda; struct lineop getscl; struct lineop init; struct spi_device *spidev; };
static struct adapter_parm adapter_parm[] = { /* type 0: National Semiconductor LM70CILD-3 evaluation board */ { .name = "lm70CILD-3", .setscl = { 0x40, DATA, 0 }, .setcsl = { 0x20, DATA, 1 }, .getsda = { 0x10, STAT, 0 }, // SI/O .init = { 0xFE, DATA, 0 }, }, /* add adapters here */ };
/*----------------Module parameters-----------------------------*/ static int type; module_param(type, int, 0); MODULE_PARM_DESC(type, "Type of adapter: (defaults to 0)\n" " 0 = LM70CILD-3 (National Semiconductor) evaluation board\n"); /* add new type(s) here */
static u16 base; module_param(base, ushort, 0); MODULE_PARM_DESC(base, "Parport Base I/O address"); /*--------------------------------------------------------------*/
#include <linux/ioport.h> #include <linux/delay.h> #include <asm/io.h>
/* ----- Low-level parallel port access ----------------------------------- */
#define DEFAULT_BASE 0x378
static inline void port_write(unsigned char p, unsigned char d) { outb(d, base+p); }
static inline unsigned char port_read(unsigned char p) { return inb(base+p); }
/* ----- Unified line operation functions --------------------------------- */
static inline void line_set(int state, const struct lineop *op) { u8 oldval = port_read(op->port);
/* Touch only the bit(s) needed */ if ((op->inverted && !state) || (!op->inverted && state)) port_write(op->port, oldval | op->val); else port_write(op->port, oldval & ~op->val); }
static inline int line_get(const struct lineop *op) { u8 oldval = port_read(op->port);
return ((op->inverted && (oldval & op->val) != op->val) || (!op->inverted && (oldval & op->val) == op->val)); }
/* ----- SPI call-back functions and structures ----------------- */
static void parport_setscl(void *data, int state) { line_set(state, &adapter_parm[type].setscl); }
static void parport_setsda(void *data, int state) { line_set(state, &adapter_parm[type].setsda); }
static int parport_getscl(void *data) { return line_get(&adapter_parm[type].getscl); }
static int parport_getsda(void *data) { return line_get(&adapter_parm[type].getsda); }
static void parport_setcsl(void *data, int state) { line_set(state, &adapter_parm[type].setcsl); }
/* ----- Module init and exit---------------------------------------------- */
/* Module init : to be called from the specific driver init routine */ static int spi_parport_init(char *name) { /* adapter_parm set in the spi-parport-light.h header; type is a module parameter */ if (type < 0 || type >= ARRAY_SIZE(adapter_parm)) { printk(KERN_WARNING "%s: invalid parameter \"type\" (%d)\n\ defaulting to type 0\n", name, type); type = 0; }
if (base == 0) base = DEFAULT_BASE;
if (!request_region(base, 3, "spi-parport-light")) return -EBUSY;
/* Reset hardware to a sane state (SCL and SDA high) */ parport_setsda(NULL, 1); parport_setscl(NULL, 1); /* Other init if needed (power on...) */ if (adapter_parm[type].init.val) line_set(1, &adapter_parm[type].init); /* CS deselect, if necessary.. */ if (adapter_parm[type].setcsl.val) line_set(0, &adapter_parm[type].setcsl);
/* Memory for the spi_device struct for this adapter */ adapter_parm[type].spidev = kzalloc(sizeof(struct spi_device), GFP_KERNEL); if (!adapter_parm[type].spidev) { printk(KERN_ERR "%s: out of memory\n", name); release_region(base, 3); return -ENOMEM; }
printk(KERN_INFO "%s loaded: adapter type %d (device '%s'), using base address 0x%x\n", name, type, adapter_parm[type].name, base);
return 0; }
/* Module exit : to be called from the specific driver cleanup routine */ static void spi_parport_exit(char *name) { if (adapter_parm[type].spidev) kfree (adapter_parm[type].spidev);
/* Un-init if needed (power off...) */ if (adapter_parm[type].init.val) line_set(0, &adapter_parm[type].init); release_region(base, 3); printk(KERN_INFO "%s unloaded.\n", name); } - 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/
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