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6fd63087d8
linux-next/drivers/spi/spi-fsl-dspi.c
Aaron Brice 6fd63087d8 spi: fsl-dspi: Fix clock rate scale values 
Previous algorithm had an outer loop with the values {2,3,5,7} and an
inner loop with {2,4,6,8,16,32,...,32768}, and would pick the first
value over the required scaling value (where the total scale was the two
numbers multiplied).

Since the inner loop went up to 32768 it would always pick a value of 2
for PBR and a much higher than necessary value for BR.  The desired
scale factor was being divided by two I believe to compensate for the
much higher scale factors (the divide by two not specified in the
reference manual).

Updated to check all values and find the smallest scale factor possible
without going over the desired clock rate.

Signed-off-by: Aaron Brice <aaron.brice@datasoft.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
2015-03-31 12:13:03 +01:00

586 lines
14 KiB
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/*
* drivers/spi/spi-fsl-dspi.c
*
* Copyright 2013 Freescale Semiconductor, Inc.
*
* Freescale DSPI driver
* This file contains a driver for the Freescale DSPI
*
* 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.
*
*/
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/regmap.h>
#include <linux/sched.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
#define DRIVER_NAME "fsl-dspi"
#define TRAN_STATE_RX_VOID 0x01
#define TRAN_STATE_TX_VOID 0x02
#define TRAN_STATE_WORD_ODD_NUM 0x04
#define DSPI_FIFO_SIZE 4
#define SPI_MCR 0x00
#define SPI_MCR_MASTER (1 << 31)
#define SPI_MCR_PCSIS (0x3F << 16)
#define SPI_MCR_CLR_TXF (1 << 11)
#define SPI_MCR_CLR_RXF (1 << 10)
#define SPI_TCR 0x08
#define SPI_CTAR(x) (0x0c + (((x) & 0x3) * 4))
#define SPI_CTAR_FMSZ(x) (((x) & 0x0000000f) << 27)
#define SPI_CTAR_CPOL(x) ((x) << 26)
#define SPI_CTAR_CPHA(x) ((x) << 25)
#define SPI_CTAR_LSBFE(x) ((x) << 24)
#define SPI_CTAR_PCSSCR(x) (((x) & 0x00000003) << 22)
#define SPI_CTAR_PASC(x) (((x) & 0x00000003) << 20)
#define SPI_CTAR_PDT(x) (((x) & 0x00000003) << 18)
#define SPI_CTAR_PBR(x) (((x) & 0x00000003) << 16)
#define SPI_CTAR_CSSCK(x) (((x) & 0x0000000f) << 12)
#define SPI_CTAR_ASC(x) (((x) & 0x0000000f) << 8)
#define SPI_CTAR_DT(x) (((x) & 0x0000000f) << 4)
#define SPI_CTAR_BR(x) ((x) & 0x0000000f)
#define SPI_CTAR0_SLAVE 0x0c
#define SPI_SR 0x2c
#define SPI_SR_EOQF 0x10000000
#define SPI_RSER 0x30
#define SPI_RSER_EOQFE 0x10000000
#define SPI_PUSHR 0x34
#define SPI_PUSHR_CONT (1 << 31)
#define SPI_PUSHR_CTAS(x) (((x) & 0x00000003) << 28)
#define SPI_PUSHR_EOQ (1 << 27)
#define SPI_PUSHR_CTCNT (1 << 26)
#define SPI_PUSHR_PCS(x) (((1 << x) & 0x0000003f) << 16)
#define SPI_PUSHR_TXDATA(x) ((x) & 0x0000ffff)
#define SPI_PUSHR_SLAVE 0x34
#define SPI_POPR 0x38
#define SPI_POPR_RXDATA(x) ((x) & 0x0000ffff)
#define SPI_TXFR0 0x3c
#define SPI_TXFR1 0x40
#define SPI_TXFR2 0x44
#define SPI_TXFR3 0x48
#define SPI_RXFR0 0x7c
#define SPI_RXFR1 0x80
#define SPI_RXFR2 0x84
#define SPI_RXFR3 0x88
#define SPI_FRAME_BITS(bits) SPI_CTAR_FMSZ((bits) - 1)
#define SPI_FRAME_BITS_MASK SPI_CTAR_FMSZ(0xf)
#define SPI_FRAME_BITS_16 SPI_CTAR_FMSZ(0xf)
#define SPI_FRAME_BITS_8 SPI_CTAR_FMSZ(0x7)
#define SPI_CS_INIT 0x01
#define SPI_CS_ASSERT 0x02
#define SPI_CS_DROP 0x04
struct chip_data {
u32 mcr_val;
u32 ctar_val;
u16 void_write_data;
};
struct fsl_dspi {
struct spi_master *master;
struct platform_device *pdev;
struct regmap *regmap;
int irq;
struct clk *clk;
struct spi_transfer *cur_transfer;
struct spi_message *cur_msg;
struct chip_data *cur_chip;
size_t len;
void *tx;
void *tx_end;
void *rx;
void *rx_end;
char dataflags;
u8 cs;
u16 void_write_data;
u32 cs_change;
wait_queue_head_t waitq;
u32 waitflags;
};
static inline int is_double_byte_mode(struct fsl_dspi *dspi)
{
unsigned int val;
regmap_read(dspi->regmap, SPI_CTAR(dspi->cs), &val);
return ((val & SPI_FRAME_BITS_MASK) == SPI_FRAME_BITS(8)) ? 0 : 1;
}
static void hz_to_spi_baud(char *pbr, char *br, int speed_hz,
unsigned long clkrate)
{
/* Valid baud rate pre-scaler values */
int pbr_tbl[4] = {2, 3, 5, 7};
int brs[16] = { 2, 4, 6, 8,
16, 32, 64, 128,
256, 512, 1024, 2048,
4096, 8192, 16384, 32768 };
int scale_needed, scale, minscale = INT_MAX;
int i, j;
scale_needed = clkrate / speed_hz;
for (i = 0; i < ARRAY_SIZE(brs); i++)
for (j = 0; j < ARRAY_SIZE(pbr_tbl); j++) {
scale = brs[i] * pbr_tbl[j];
if (scale >= scale_needed) {
if (scale < minscale) {
minscale = scale;
*br = i;
*pbr = j;
}
break;
}
}
if (minscale == INT_MAX) {
pr_warn("Can not find valid baud rate,speed_hz is %d,clkrate is %ld, we use the max prescaler value.\n",
speed_hz, clkrate);
*pbr = ARRAY_SIZE(pbr_tbl) - 1;
*br = ARRAY_SIZE(brs) - 1;
}
}
static int dspi_transfer_write(struct fsl_dspi *dspi)
{
int tx_count = 0;
int tx_word;
u16 d16;
u8 d8;
u32 dspi_pushr = 0;
int first = 1;
tx_word = is_double_byte_mode(dspi);
/* If we are in word mode, but only have a single byte to transfer
* then switch to byte mode temporarily. Will switch back at the
* end of the transfer.
*/
if (tx_word && (dspi->len == 1)) {
dspi->dataflags |= TRAN_STATE_WORD_ODD_NUM;
regmap_update_bits(dspi->regmap, SPI_CTAR(dspi->cs),
SPI_FRAME_BITS_MASK, SPI_FRAME_BITS(8));
tx_word = 0;
}
while (dspi->len && (tx_count < DSPI_FIFO_SIZE)) {
if (tx_word) {
if (dspi->len == 1)
break;
if (!(dspi->dataflags & TRAN_STATE_TX_VOID)) {
d16 = *(u16 *)dspi->tx;
dspi->tx += 2;
} else {
d16 = dspi->void_write_data;
}
dspi_pushr = SPI_PUSHR_TXDATA(d16) |
SPI_PUSHR_PCS(dspi->cs) |
SPI_PUSHR_CTAS(dspi->cs) |
SPI_PUSHR_CONT;
dspi->len -= 2;
} else {
if (!(dspi->dataflags & TRAN_STATE_TX_VOID)) {
d8 = *(u8 *)dspi->tx;
dspi->tx++;
} else {
d8 = (u8)dspi->void_write_data;
}
dspi_pushr = SPI_PUSHR_TXDATA(d8) |
SPI_PUSHR_PCS(dspi->cs) |
SPI_PUSHR_CTAS(dspi->cs) |
SPI_PUSHR_CONT;
dspi->len--;
}
if (dspi->len == 0 || tx_count == DSPI_FIFO_SIZE - 1) {
/* last transfer in the transfer */
dspi_pushr |= SPI_PUSHR_EOQ;
if ((dspi->cs_change) && (!dspi->len))
dspi_pushr &= ~SPI_PUSHR_CONT;
} else if (tx_word && (dspi->len == 1))
dspi_pushr |= SPI_PUSHR_EOQ;
if (first) {
first = 0;
dspi_pushr |= SPI_PUSHR_CTCNT; /* clear counter */
}
regmap_write(dspi->regmap, SPI_PUSHR, dspi_pushr);
tx_count++;
}
return tx_count * (tx_word + 1);
}
static int dspi_transfer_read(struct fsl_dspi *dspi)
{
int rx_count = 0;
int rx_word = is_double_byte_mode(dspi);
u16 d;
while ((dspi->rx < dspi->rx_end)
&& (rx_count < DSPI_FIFO_SIZE)) {
if (rx_word) {
unsigned int val;
if ((dspi->rx_end - dspi->rx) == 1)
break;
regmap_read(dspi->regmap, SPI_POPR, &val);
d = SPI_POPR_RXDATA(val);
if (!(dspi->dataflags & TRAN_STATE_RX_VOID))
*(u16 *)dspi->rx = d;
dspi->rx += 2;
} else {
unsigned int val;
regmap_read(dspi->regmap, SPI_POPR, &val);
d = SPI_POPR_RXDATA(val);
if (!(dspi->dataflags & TRAN_STATE_RX_VOID))
*(u8 *)dspi->rx = d;
dspi->rx++;
}
rx_count++;
}
return rx_count;
}
static int dspi_transfer_one_message(struct spi_master *master,
struct spi_message *message)
{
struct fsl_dspi *dspi = spi_master_get_devdata(master);
struct spi_device *spi = message->spi;
struct spi_transfer *transfer;
int status = 0;
message->actual_length = 0;
list_for_each_entry(transfer, &message->transfers, transfer_list) {
dspi->cur_transfer = transfer;
dspi->cur_msg = message;
dspi->cur_chip = spi_get_ctldata(spi);
dspi->cs = spi->chip_select;
if (dspi->cur_transfer->transfer_list.next
== &dspi->cur_msg->transfers)
transfer->cs_change = 1;
dspi->cs_change = transfer->cs_change;
dspi->void_write_data = dspi->cur_chip->void_write_data;
dspi->dataflags = 0;
dspi->tx = (void *)transfer->tx_buf;
dspi->tx_end = dspi->tx + transfer->len;
dspi->rx = transfer->rx_buf;
dspi->rx_end = dspi->rx + transfer->len;
dspi->len = transfer->len;
if (!dspi->rx)
dspi->dataflags |= TRAN_STATE_RX_VOID;
if (!dspi->tx)
dspi->dataflags |= TRAN_STATE_TX_VOID;
regmap_write(dspi->regmap, SPI_MCR, dspi->cur_chip->mcr_val);
regmap_update_bits(dspi->regmap, SPI_MCR,
SPI_MCR_CLR_TXF | SPI_MCR_CLR_RXF,
SPI_MCR_CLR_TXF | SPI_MCR_CLR_RXF);
regmap_write(dspi->regmap, SPI_CTAR(dspi->cs),
dspi->cur_chip->ctar_val);
if (transfer->speed_hz)
regmap_write(dspi->regmap, SPI_CTAR(dspi->cs),
dspi->cur_chip->ctar_val);
regmap_write(dspi->regmap, SPI_RSER, SPI_RSER_EOQFE);
message->actual_length += dspi_transfer_write(dspi);
if (wait_event_interruptible(dspi->waitq, dspi->waitflags))
dev_err(&dspi->pdev->dev, "wait transfer complete fail!\n");
dspi->waitflags = 0;
if (transfer->delay_usecs)
udelay(transfer->delay_usecs);
}
message->status = status;
spi_finalize_current_message(master);
return status;
}
static int dspi_setup(struct spi_device *spi)
{
struct chip_data *chip;
struct fsl_dspi *dspi = spi_master_get_devdata(spi->master);
unsigned char br = 0, pbr = 0, fmsz = 0;
if ((spi->bits_per_word >= 4) && (spi->bits_per_word <= 16)) {
fmsz = spi->bits_per_word - 1;
} else {
pr_err("Invalid wordsize\n");
return -ENODEV;
}
/* Only alloc on first setup */
chip = spi_get_ctldata(spi);
if (chip == NULL) {
chip = kzalloc(sizeof(struct chip_data), GFP_KERNEL);
if (!chip)
return -ENOMEM;
}
chip->mcr_val = SPI_MCR_MASTER | SPI_MCR_PCSIS |
SPI_MCR_CLR_TXF | SPI_MCR_CLR_RXF;
chip->void_write_data = 0;
hz_to_spi_baud(&pbr, &br,
spi->max_speed_hz, clk_get_rate(dspi->clk));
chip->ctar_val = SPI_CTAR_FMSZ(fmsz)
| SPI_CTAR_CPOL(spi->mode & SPI_CPOL ? 1 : 0)
| SPI_CTAR_CPHA(spi->mode & SPI_CPHA ? 1 : 0)
| SPI_CTAR_LSBFE(spi->mode & SPI_LSB_FIRST ? 1 : 0)
| SPI_CTAR_PBR(pbr)
| SPI_CTAR_BR(br);
spi_set_ctldata(spi, chip);
return 0;
}
static void dspi_cleanup(struct spi_device *spi)
{
struct chip_data *chip = spi_get_ctldata((struct spi_device *)spi);
dev_dbg(&spi->dev, "spi_device %u.%u cleanup\n",
spi->master->bus_num, spi->chip_select);
kfree(chip);
}
static irqreturn_t dspi_interrupt(int irq, void *dev_id)
{
struct fsl_dspi *dspi = (struct fsl_dspi *)dev_id;
struct spi_message *msg = dspi->cur_msg;
regmap_write(dspi->regmap, SPI_SR, SPI_SR_EOQF);
dspi_transfer_read(dspi);
if (!dspi->len) {
if (dspi->dataflags & TRAN_STATE_WORD_ODD_NUM)
regmap_update_bits(dspi->regmap, SPI_CTAR(dspi->cs),
SPI_FRAME_BITS_MASK, SPI_FRAME_BITS(16));
dspi->waitflags = 1;
wake_up_interruptible(&dspi->waitq);
} else
msg->actual_length += dspi_transfer_write(dspi);
return IRQ_HANDLED;
}
static const struct of_device_id fsl_dspi_dt_ids[] = {
{ .compatible = "fsl,vf610-dspi", .data = NULL, },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, fsl_dspi_dt_ids);
#ifdef CONFIG_PM_SLEEP
static int dspi_suspend(struct device *dev)
{
struct spi_master *master = dev_get_drvdata(dev);
struct fsl_dspi *dspi = spi_master_get_devdata(master);
spi_master_suspend(master);
clk_disable_unprepare(dspi->clk);
return 0;
}
static int dspi_resume(struct device *dev)
{
struct spi_master *master = dev_get_drvdata(dev);
struct fsl_dspi *dspi = spi_master_get_devdata(master);
clk_prepare_enable(dspi->clk);
spi_master_resume(master);
return 0;
}
#endif /* CONFIG_PM_SLEEP */
static SIMPLE_DEV_PM_OPS(dspi_pm, dspi_suspend, dspi_resume);
static const struct regmap_config dspi_regmap_config = {
.reg_bits = 32,
.val_bits = 32,
.reg_stride = 4,
.max_register = 0x88,
};
static int dspi_probe(struct platform_device *pdev)
{
struct device_node *np = pdev->dev.of_node;
struct spi_master *master;
struct fsl_dspi *dspi;
struct resource *res;
void __iomem *base;
int ret = 0, cs_num, bus_num;
master = spi_alloc_master(&pdev->dev, sizeof(struct fsl_dspi));
if (!master)
return -ENOMEM;
dspi = spi_master_get_devdata(master);
dspi->pdev = pdev;
dspi->master = master;
master->transfer = NULL;
master->setup = dspi_setup;
master->transfer_one_message = dspi_transfer_one_message;
master->dev.of_node = pdev->dev.of_node;
master->cleanup = dspi_cleanup;
master->mode_bits = SPI_CPOL | SPI_CPHA;
master->bits_per_word_mask = SPI_BPW_MASK(4) | SPI_BPW_MASK(8) |
SPI_BPW_MASK(16);
ret = of_property_read_u32(np, "spi-num-chipselects", &cs_num);
if (ret < 0) {
dev_err(&pdev->dev, "can't get spi-num-chipselects\n");
goto out_master_put;
}
master->num_chipselect = cs_num;
ret = of_property_read_u32(np, "bus-num", &bus_num);
if (ret < 0) {
dev_err(&pdev->dev, "can't get bus-num\n");
goto out_master_put;
}
master->bus_num = bus_num;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(base)) {
ret = PTR_ERR(base);
goto out_master_put;
}
dspi->regmap = devm_regmap_init_mmio_clk(&pdev->dev, "dspi", base,
&dspi_regmap_config);
if (IS_ERR(dspi->regmap)) {
dev_err(&pdev->dev, "failed to init regmap: %ld\n",
PTR_ERR(dspi->regmap));
return PTR_ERR(dspi->regmap);
}
dspi->irq = platform_get_irq(pdev, 0);
if (dspi->irq < 0) {
dev_err(&pdev->dev, "can't get platform irq\n");
ret = dspi->irq;
goto out_master_put;
}
ret = devm_request_irq(&pdev->dev, dspi->irq, dspi_interrupt, 0,
pdev->name, dspi);
if (ret < 0) {
dev_err(&pdev->dev, "Unable to attach DSPI interrupt\n");
goto out_master_put;
}
dspi->clk = devm_clk_get(&pdev->dev, "dspi");
if (IS_ERR(dspi->clk)) {
ret = PTR_ERR(dspi->clk);
dev_err(&pdev->dev, "unable to get clock\n");
goto out_master_put;
}
clk_prepare_enable(dspi->clk);
init_waitqueue_head(&dspi->waitq);
platform_set_drvdata(pdev, master);
ret = spi_register_master(master);
if (ret != 0) {
dev_err(&pdev->dev, "Problem registering DSPI master\n");
goto out_clk_put;
}
return ret;
out_clk_put:
clk_disable_unprepare(dspi->clk);
out_master_put:
spi_master_put(master);
return ret;
}
static int dspi_remove(struct platform_device *pdev)
{
struct spi_master *master = platform_get_drvdata(pdev);
struct fsl_dspi *dspi = spi_master_get_devdata(master);
/* Disconnect from the SPI framework */
clk_disable_unprepare(dspi->clk);
spi_unregister_master(dspi->master);
spi_master_put(dspi->master);
return 0;
}
static struct platform_driver fsl_dspi_driver = {
.driver.name = DRIVER_NAME,
.driver.of_match_table = fsl_dspi_dt_ids,
.driver.owner = THIS_MODULE,
.driver.pm = &dspi_pm,
.probe = dspi_probe,
.remove = dspi_remove,
};
module_platform_driver(fsl_dspi_driver);
MODULE_DESCRIPTION("Freescale DSPI Controller Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRIVER_NAME);
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