linux/drivers/spi/spi-fsl-lpspi.c
Gao Pan 5314987de5 spi: imx: add lpspi bus driver
This patch adds lpspi driver to support new i.MX products which use
lpspi instead of ecspi.

The lpspi can continue operating in stop mode when an appropriate
clock is available. It is also designed for low CPU overhead with
DMA offloading of FIFO register accesses.

Signed-off-by: Gao Pan <pandy.gao@nxp.com>
Reviewed-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
2016-11-22 19:13:16 +00:00

513 lines
12 KiB
C

/*
* Freescale i.MX7ULP LPSPI driver
*
* Copyright 2016 Freescale Semiconductor, Inc.
*
* 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.
*
*/
#include <linux/clk.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/irq.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/slab.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
#include <linux/types.h>
#define DRIVER_NAME "fsl_lpspi"
/* i.MX7ULP LPSPI registers */
#define IMX7ULP_VERID 0x0
#define IMX7ULP_PARAM 0x4
#define IMX7ULP_CR 0x10
#define IMX7ULP_SR 0x14
#define IMX7ULP_IER 0x18
#define IMX7ULP_DER 0x1c
#define IMX7ULP_CFGR0 0x20
#define IMX7ULP_CFGR1 0x24
#define IMX7ULP_DMR0 0x30
#define IMX7ULP_DMR1 0x34
#define IMX7ULP_CCR 0x40
#define IMX7ULP_FCR 0x58
#define IMX7ULP_FSR 0x5c
#define IMX7ULP_TCR 0x60
#define IMX7ULP_TDR 0x64
#define IMX7ULP_RSR 0x70
#define IMX7ULP_RDR 0x74
/* General control register field define */
#define CR_RRF BIT(9)
#define CR_RTF BIT(8)
#define CR_RST BIT(1)
#define CR_MEN BIT(0)
#define SR_TCF BIT(10)
#define SR_RDF BIT(1)
#define SR_TDF BIT(0)
#define IER_TCIE BIT(10)
#define IER_RDIE BIT(1)
#define IER_TDIE BIT(0)
#define CFGR1_PCSCFG BIT(27)
#define CFGR1_PCSPOL BIT(8)
#define CFGR1_NOSTALL BIT(3)
#define CFGR1_MASTER BIT(0)
#define RSR_RXEMPTY BIT(1)
#define TCR_CPOL BIT(31)
#define TCR_CPHA BIT(30)
#define TCR_CONT BIT(21)
#define TCR_CONTC BIT(20)
#define TCR_RXMSK BIT(19)
#define TCR_TXMSK BIT(18)
static int clkdivs[] = {1, 2, 4, 8, 16, 32, 64, 128};
struct lpspi_config {
u8 bpw;
u8 chip_select;
u8 prescale;
u16 mode;
u32 speed_hz;
};
struct fsl_lpspi_data {
struct device *dev;
void __iomem *base;
struct clk *clk;
void *rx_buf;
const void *tx_buf;
void (*tx)(struct fsl_lpspi_data *);
void (*rx)(struct fsl_lpspi_data *);
u32 remain;
u8 txfifosize;
u8 rxfifosize;
struct lpspi_config config;
struct completion xfer_done;
};
static const struct of_device_id fsl_lpspi_dt_ids[] = {
{ .compatible = "fsl,imx7ulp-spi", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, fsl_lpspi_dt_ids);
#define LPSPI_BUF_RX(type) \
static void fsl_lpspi_buf_rx_##type(struct fsl_lpspi_data *fsl_lpspi) \
{ \
unsigned int val = readl(fsl_lpspi->base + IMX7ULP_RDR); \
\
if (fsl_lpspi->rx_buf) { \
*(type *)fsl_lpspi->rx_buf = val; \
fsl_lpspi->rx_buf += sizeof(type); \
} \
}
#define LPSPI_BUF_TX(type) \
static void fsl_lpspi_buf_tx_##type(struct fsl_lpspi_data *fsl_lpspi) \
{ \
type val = 0; \
\
if (fsl_lpspi->tx_buf) { \
val = *(type *)fsl_lpspi->tx_buf; \
fsl_lpspi->tx_buf += sizeof(type); \
} \
\
fsl_lpspi->remain -= sizeof(type); \
writel(val, fsl_lpspi->base + IMX7ULP_TDR); \
}
LPSPI_BUF_RX(u8)
LPSPI_BUF_TX(u8)
LPSPI_BUF_RX(u16)
LPSPI_BUF_TX(u16)
LPSPI_BUF_RX(u32)
LPSPI_BUF_TX(u32)
static void fsl_lpspi_intctrl(struct fsl_lpspi_data *fsl_lpspi,
unsigned int enable)
{
writel(enable, fsl_lpspi->base + IMX7ULP_IER);
}
static int fsl_lpspi_prepare_message(struct spi_master *master,
struct spi_message *msg)
{
struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
return clk_prepare_enable(fsl_lpspi->clk);
}
static int
fsl_lpspi_unprepare_message(struct spi_master *master, struct spi_message *msg)
{
struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
clk_disable_unprepare(fsl_lpspi->clk);
return 0;
}
static int fsl_lpspi_txfifo_empty(struct fsl_lpspi_data *fsl_lpspi)
{
u32 txcnt;
unsigned long orig_jiffies = jiffies;
do {
txcnt = readl(fsl_lpspi->base + IMX7ULP_FSR) & 0xff;
if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500))) {
dev_dbg(fsl_lpspi->dev, "txfifo empty timeout\n");
return -ETIMEDOUT;
}
schedule();
} while (txcnt);
return 0;
}
static void fsl_lpspi_write_tx_fifo(struct fsl_lpspi_data *fsl_lpspi)
{
u8 txfifo_cnt;
txfifo_cnt = readl(fsl_lpspi->base + IMX7ULP_FSR) & 0xff;
while (txfifo_cnt < fsl_lpspi->txfifosize) {
if (!fsl_lpspi->remain)
break;
fsl_lpspi->tx(fsl_lpspi);
txfifo_cnt++;
}
if (!fsl_lpspi->remain && (txfifo_cnt < fsl_lpspi->txfifosize))
writel(0, fsl_lpspi->base + IMX7ULP_TDR);
else
fsl_lpspi_intctrl(fsl_lpspi, IER_TDIE);
}
static void fsl_lpspi_read_rx_fifo(struct fsl_lpspi_data *fsl_lpspi)
{
while (!(readl(fsl_lpspi->base + IMX7ULP_RSR) & RSR_RXEMPTY))
fsl_lpspi->rx(fsl_lpspi);
}
static void fsl_lpspi_set_cmd(struct fsl_lpspi_data *fsl_lpspi,
bool is_first_xfer)
{
u32 temp = 0;
temp |= fsl_lpspi->config.bpw - 1;
temp |= fsl_lpspi->config.prescale << 27;
temp |= (fsl_lpspi->config.mode & 0x11) << 30;
temp |= (fsl_lpspi->config.chip_select & 0x3) << 24;
/*
* Set TCR_CONT will keep SS asserted after current transfer.
* For the first transfer, clear TCR_CONTC to assert SS.
* For subsequent transfer, set TCR_CONTC to keep SS asserted.
*/
temp |= TCR_CONT;
if (is_first_xfer)
temp &= ~TCR_CONTC;
else
temp |= TCR_CONTC;
writel(temp, fsl_lpspi->base + IMX7ULP_TCR);
dev_dbg(fsl_lpspi->dev, "TCR=0x%x\n", temp);
}
static void fsl_lpspi_set_watermark(struct fsl_lpspi_data *fsl_lpspi)
{
u8 txwatermark, rxwatermark;
u32 temp;
temp = readl(fsl_lpspi->base + IMX7ULP_PARAM);
fsl_lpspi->txfifosize = 1 << (temp & 0x0f);
fsl_lpspi->rxfifosize = 1 << ((temp >> 8) & 0x0f);
rxwatermark = fsl_lpspi->txfifosize >> 1;
txwatermark = fsl_lpspi->rxfifosize >> 1;
temp = txwatermark | rxwatermark << 16;
writel(temp, fsl_lpspi->base + IMX7ULP_FCR);
dev_dbg(fsl_lpspi->dev, "FCR=0x%x\n", temp);
}
static int fsl_lpspi_set_bitrate(struct fsl_lpspi_data *fsl_lpspi)
{
struct lpspi_config config = fsl_lpspi->config;
unsigned int perclk_rate, scldiv;
u8 prescale;
perclk_rate = clk_get_rate(fsl_lpspi->clk);
for (prescale = 0; prescale < 8; prescale++) {
scldiv = perclk_rate /
(clkdivs[prescale] * config.speed_hz) - 2;
if (scldiv < 256) {
fsl_lpspi->config.prescale = prescale;
break;
}
}
if (prescale == 8 && scldiv >= 256)
return -EINVAL;
writel(scldiv, fsl_lpspi->base + IMX7ULP_CCR);
dev_dbg(fsl_lpspi->dev, "perclk=%d, speed=%d, prescale =%d, scldiv=%d\n",
perclk_rate, config.speed_hz, prescale, scldiv);
return 0;
}
static int fsl_lpspi_config(struct fsl_lpspi_data *fsl_lpspi)
{
u32 temp;
int ret;
temp = CR_RST;
writel(temp, fsl_lpspi->base + IMX7ULP_CR);
writel(0, fsl_lpspi->base + IMX7ULP_CR);
ret = fsl_lpspi_set_bitrate(fsl_lpspi);
if (ret)
return ret;
fsl_lpspi_set_watermark(fsl_lpspi);
temp = CFGR1_PCSCFG | CFGR1_MASTER | CFGR1_NOSTALL;
if (fsl_lpspi->config.mode & SPI_CS_HIGH)
temp |= CFGR1_PCSPOL;
writel(temp, fsl_lpspi->base + IMX7ULP_CFGR1);
temp = readl(fsl_lpspi->base + IMX7ULP_CR);
temp |= CR_RRF | CR_RTF | CR_MEN;
writel(temp, fsl_lpspi->base + IMX7ULP_CR);
return 0;
}
static void fsl_lpspi_setup_transfer(struct spi_device *spi,
struct spi_transfer *t)
{
struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(spi->master);
fsl_lpspi->config.mode = spi->mode;
fsl_lpspi->config.bpw = t ? t->bits_per_word : spi->bits_per_word;
fsl_lpspi->config.speed_hz = t ? t->speed_hz : spi->max_speed_hz;
fsl_lpspi->config.chip_select = spi->chip_select;
if (!fsl_lpspi->config.speed_hz)
fsl_lpspi->config.speed_hz = spi->max_speed_hz;
if (!fsl_lpspi->config.bpw)
fsl_lpspi->config.bpw = spi->bits_per_word;
/* Initialize the functions for transfer */
if (fsl_lpspi->config.bpw <= 8) {
fsl_lpspi->rx = fsl_lpspi_buf_rx_u8;
fsl_lpspi->tx = fsl_lpspi_buf_tx_u8;
} else if (fsl_lpspi->config.bpw <= 16) {
fsl_lpspi->rx = fsl_lpspi_buf_rx_u16;
fsl_lpspi->tx = fsl_lpspi_buf_tx_u16;
} else {
fsl_lpspi->rx = fsl_lpspi_buf_rx_u32;
fsl_lpspi->tx = fsl_lpspi_buf_tx_u32;
}
fsl_lpspi_config(fsl_lpspi);
}
static int fsl_lpspi_transfer_one(struct spi_master *master,
struct spi_device *spi,
struct spi_transfer *t)
{
struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
int ret;
fsl_lpspi->tx_buf = t->tx_buf;
fsl_lpspi->rx_buf = t->rx_buf;
fsl_lpspi->remain = t->len;
reinit_completion(&fsl_lpspi->xfer_done);
fsl_lpspi_write_tx_fifo(fsl_lpspi);
wait_for_completion(&fsl_lpspi->xfer_done);
ret = fsl_lpspi_txfifo_empty(fsl_lpspi);
fsl_lpspi_read_rx_fifo(fsl_lpspi);
return ret;
}
static int fsl_lpspi_transfer_one_msg(struct spi_master *master,
struct spi_message *msg)
{
struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
struct spi_device *spi = msg->spi;
struct spi_transfer *xfer;
bool is_first_xfer = true;
u32 temp;
int ret;
msg->status = 0;
msg->actual_length = 0;
list_for_each_entry(xfer, &msg->transfers, transfer_list) {
fsl_lpspi_setup_transfer(spi, xfer);
fsl_lpspi_set_cmd(fsl_lpspi, is_first_xfer);
is_first_xfer = false;
ret = fsl_lpspi_transfer_one(master, spi, xfer);
if (ret < 0)
goto complete;
msg->actual_length += xfer->len;
}
complete:
/* de-assert SS, then finalize current message */
temp = readl(fsl_lpspi->base + IMX7ULP_TCR);
temp &= ~TCR_CONTC;
writel(temp, fsl_lpspi->base + IMX7ULP_TCR);
msg->status = ret;
spi_finalize_current_message(master);
return ret;
}
static irqreturn_t fsl_lpspi_isr(int irq, void *dev_id)
{
struct fsl_lpspi_data *fsl_lpspi = dev_id;
u32 temp;
fsl_lpspi_intctrl(fsl_lpspi, 0);
temp = readl(fsl_lpspi->base + IMX7ULP_SR);
fsl_lpspi_read_rx_fifo(fsl_lpspi);
if (temp & SR_TDF) {
fsl_lpspi_write_tx_fifo(fsl_lpspi);
if (!fsl_lpspi->remain)
complete(&fsl_lpspi->xfer_done);
return IRQ_HANDLED;
}
return IRQ_NONE;
}
static int fsl_lpspi_probe(struct platform_device *pdev)
{
struct fsl_lpspi_data *fsl_lpspi;
struct spi_master *master;
struct resource *res;
int ret, irq;
master = spi_alloc_master(&pdev->dev, sizeof(struct fsl_lpspi_data));
if (!master)
return -ENOMEM;
platform_set_drvdata(pdev, master);
master->bits_per_word_mask = SPI_BPW_RANGE_MASK(8, 32);
master->bus_num = pdev->id;
fsl_lpspi = spi_master_get_devdata(master);
fsl_lpspi->dev = &pdev->dev;
master->transfer_one_message = fsl_lpspi_transfer_one_msg;
master->prepare_message = fsl_lpspi_prepare_message;
master->unprepare_message = fsl_lpspi_unprepare_message;
master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
master->flags = SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX;
master->dev.of_node = pdev->dev.of_node;
master->bus_num = pdev->id;
init_completion(&fsl_lpspi->xfer_done);
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
fsl_lpspi->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(fsl_lpspi->base)) {
ret = PTR_ERR(fsl_lpspi->base);
goto out_master_put;
}
irq = platform_get_irq(pdev, 0);
if (irq < 0) {
ret = irq;
goto out_master_put;
}
ret = devm_request_irq(&pdev->dev, irq, fsl_lpspi_isr, 0,
dev_name(&pdev->dev), fsl_lpspi);
if (ret) {
dev_err(&pdev->dev, "can't get irq%d: %d\n", irq, ret);
goto out_master_put;
}
fsl_lpspi->clk = devm_clk_get(&pdev->dev, "ipg");
if (IS_ERR(fsl_lpspi->clk)) {
ret = PTR_ERR(fsl_lpspi->clk);
goto out_master_put;
}
ret = devm_spi_register_master(&pdev->dev, master);
if (ret < 0) {
dev_err(&pdev->dev, "spi_register_master error.\n");
goto out_master_put;
}
return 0;
out_master_put:
spi_master_put(master);
return ret;
}
static int fsl_lpspi_remove(struct platform_device *pdev)
{
struct spi_master *master = platform_get_drvdata(pdev);
struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
clk_disable_unprepare(fsl_lpspi->clk);
return 0;
}
static struct platform_driver fsl_lpspi_driver = {
.driver = {
.name = DRIVER_NAME,
.of_match_table = fsl_lpspi_dt_ids,
},
.probe = fsl_lpspi_probe,
.remove = fsl_lpspi_remove,
};
module_platform_driver(fsl_lpspi_driver);
MODULE_DESCRIPTION("LPSPI Master Controller driver");
MODULE_AUTHOR("Gao Pan <pandy.gao@nxp.com>");
MODULE_LICENSE("GPL v2");