1 // SPDX-License-Identifier: GPL-2.0-or-later
3  * Driver for LM70EVAL-LLP board for the LM70 sensor
23  * The LM70 communicates with a host processor using a 3-wire variant of
26  * port to bitbang an SPI-parport bridge.  Accordingly, this is an SPI
28  * driver", layered on top of this one and usable without the lm70llp.
33  * The schematic for this particular board (the LM70EVAL-LLP) is
37  * Also see Documentation/spi/spi-lm70llp.rst.  The SPI<->parport code here is
38  * (heavily) based on spi-butterfly by David Brownell.
44  *  -----------  ---------  ------------
45  *      D0    2      -         -
46  *      D1    3     -->      V+   5
47  *      D2    4     -->      V+   5
48  *      D3    5     -->      V+   5
49  *      D4    6     -->      V+   5
50  *      D5    7     -->      nCS  8
51  *      D6    8     -->      SCLK 3
52  *      D7    9     -->      SI/O 5
53  *     GND   25      -       GND  7
54  *    Select 13     <--      SI/O 1
61 #define DRVNAME		"spi-lm70llp"
68 /*-------------------------------------------------------------------------*/
82 /*-------------------------------------------------------------------*/
86 	return spi->controller_data;  in spidev_to_pp()
89 /*---------------------- LM70 LLP eval board-specific inlines follow */
98 	u8 data = parport_read_data(pp->port);  in deassertCS()
100 	data &= ~0x80;		/* pull D7/SI-out low while de-asserted */  in deassertCS()
101 	parport_write_data(pp->port, data | nCS);  in deassertCS()
106 	u8 data = parport_read_data(pp->port);  in assertCS()
108 	data |= 0x80;		/* pull D7/SI-out high so lm70 drives SO-in */  in assertCS()
109 	parport_write_data(pp->port, data & ~nCS);  in assertCS()
114 	u8 data = parport_read_data(pp->port);  in clkHigh()
116 	parport_write_data(pp->port, data | SCLK);  in clkHigh()
121 	u8 data = parport_read_data(pp->port);  in clkLow()
123 	parport_write_data(pp->port, data & ~SCLK);  in clkLow()
126 /*------------------------- SPI-LM70-specific inlines ----------------------*/
153  * Why do we return 0 when the SIO line is high and vice-versa?
156  * switches it to low reflecting this on the parport (pin 13), and vice-versa.
162 	return ((SIO == (parport_read_status(pp->port) & SIO)) ? 0 : 1);  in getmiso()
165 /*--------------------------------------------------------------------*/
167 #include "spi-bitbang-txrx.h"
205 	host = spi_alloc_host(p->physport->dev, sizeof(*pp));  in spi_lm70llp_attach()
207 		status = -ENOMEM;  in spi_lm70llp_attach()
215 	pp->bitbang.ctlr = host;  in spi_lm70llp_attach()
216 	pp->bitbang.chipselect = lm70_chipselect;  in spi_lm70llp_attach()
217 	pp->bitbang.txrx_word[SPI_MODE_0] = lm70_txrx;  in spi_lm70llp_attach()
218 	pp->bitbang.flags = SPI_3WIRE;  in spi_lm70llp_attach()
223 	pp->port = p;  in spi_lm70llp_attach()
230 		status = -ENOMEM;  in spi_lm70llp_attach()
233 	pp->pd = pd;  in spi_lm70llp_attach()
242 	status = spi_bitbang_start(&pp->bitbang);  in spi_lm70llp_attach()
244 		dev_warn(&pd->dev, "spi_bitbang_start failed with status %d\n",  in spi_lm70llp_attach()
255 	strcpy(pp->info.modalias, "lm70");  in spi_lm70llp_attach()
256 	pp->info.max_speed_hz = 6 * 1000 * 1000;  in spi_lm70llp_attach()
257 	pp->info.chip_select = 0;  in spi_lm70llp_attach()
258 	pp->info.mode = SPI_3WIRE | SPI_MODE_0;  in spi_lm70llp_attach()
261 	parport_write_data(pp->port, lm70_INIT);  in spi_lm70llp_attach()
266 	pp->info.controller_data = pp;  in spi_lm70llp_attach()
267 	pp->spidev_lm70 = spi_new_device(pp->bitbang.ctlr, &pp->info);  in spi_lm70llp_attach()
268 	if (pp->spidev_lm70)  in spi_lm70llp_attach()
269 		dev_dbg(&pp->spidev_lm70->dev, "spidev_lm70 at %s\n",  in spi_lm70llp_attach()
270 			dev_name(&pp->spidev_lm70->dev));  in spi_lm70llp_attach()
272 		dev_warn(&pd->dev, "spi_new_device failed\n");  in spi_lm70llp_attach()
273 		status = -ENODEV;  in spi_lm70llp_attach()
276 	pp->spidev_lm70->bits_per_word = 8;  in spi_lm70llp_attach()
282 	spi_bitbang_stop(&pp->bitbang);  in spi_lm70llp_attach()
285 	parport_write_data(pp->port, 0);  in spi_lm70llp_attach()
287 	parport_release(pp->pd);  in spi_lm70llp_attach()
300 	if (!lm70llp || lm70llp->port != p)  in spi_lm70llp_detach()
304 	spi_bitbang_stop(&pp->bitbang);  in spi_lm70llp_detach()
307 	parport_write_data(pp->port, 0);  in spi_lm70llp_detach()
309 	parport_release(pp->pd);  in spi_lm70llp_detach()
310 	parport_unregister_device(pp->pd);  in spi_lm70llp_detach()
312 	spi_controller_put(pp->bitbang.ctlr);  in spi_lm70llp_detach()