u-boot/drivers/spi/pl022_spi.c
Quentin Schulz 8a4791fa08 spi: add support for ARM PL022 SPI controller
This adds support for the ARM PL022 SPI controller for the standard
variant (0x00041022) which has a 16bit wide and 8 locations deep TX/RX
FIFO.

A few parts were borrowed from the Linux kernel driver.

Cc: Armando Visconti <armando.visconti@st.com>
Cc: Vipin Kumar <vipin.kumar@st.com>
Signed-off-by: Quentin Schulz <quentin.schulz@bootlin.com>
2018-09-25 21:49:18 -04:00

338 lines
7.7 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* (C) Copyright 2012
* Armando Visconti, ST Microelectronics, armando.visconti@st.com.
*
* (C) Copyright 2018
* Quentin Schulz, Bootlin, quentin.schulz@bootlin.com
*
* Driver for ARM PL022 SPI Controller.
*/
#include <asm/io.h>
#include <clk.h>
#include <common.h>
#include <dm.h>
#include <dm/platform_data/pl022_spi.h>
#include <fdtdec.h>
#include <linux/bitops.h>
#include <linux/bug.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <spi.h>
#define SSP_CR0 0x000
#define SSP_CR1 0x004
#define SSP_DR 0x008
#define SSP_SR 0x00C
#define SSP_CPSR 0x010
#define SSP_IMSC 0x014
#define SSP_RIS 0x018
#define SSP_MIS 0x01C
#define SSP_ICR 0x020
#define SSP_DMACR 0x024
#define SSP_CSR 0x030 /* vendor extension */
#define SSP_ITCR 0x080
#define SSP_ITIP 0x084
#define SSP_ITOP 0x088
#define SSP_TDR 0x08C
#define SSP_PID0 0xFE0
#define SSP_PID1 0xFE4
#define SSP_PID2 0xFE8
#define SSP_PID3 0xFEC
#define SSP_CID0 0xFF0
#define SSP_CID1 0xFF4
#define SSP_CID2 0xFF8
#define SSP_CID3 0xFFC
/* SSP Control Register 0 - SSP_CR0 */
#define SSP_CR0_SPO (0x1 << 6)
#define SSP_CR0_SPH (0x1 << 7)
#define SSP_CR0_BIT_MODE(x) ((x) - 1)
#define SSP_SCR_MIN (0x00)
#define SSP_SCR_MAX (0xFF)
#define SSP_SCR_SHFT 8
#define DFLT_CLKRATE 2
/* SSP Control Register 1 - SSP_CR1 */
#define SSP_CR1_MASK_SSE (0x1 << 1)
#define SSP_CPSR_MIN (0x02)
#define SSP_CPSR_MAX (0xFE)
#define DFLT_PRESCALE (0x40)
/* SSP Status Register - SSP_SR */
#define SSP_SR_MASK_TFE (0x1 << 0) /* Transmit FIFO empty */
#define SSP_SR_MASK_TNF (0x1 << 1) /* Transmit FIFO not full */
#define SSP_SR_MASK_RNE (0x1 << 2) /* Receive FIFO not empty */
#define SSP_SR_MASK_RFF (0x1 << 3) /* Receive FIFO full */
#define SSP_SR_MASK_BSY (0x1 << 4) /* Busy Flag */
struct pl022_spi_slave {
void *base;
#if !CONFIG_IS_ENABLED(OF_PLATDATA)
struct clk clk;
#else
unsigned int freq;
#endif
};
/*
* ARM PL022 exists in different 'flavors'.
* This drivers currently support the standard variant (0x00041022), that has a
* 16bit wide and 8 locations deep TX/RX FIFO.
*/
static int pl022_is_supported(struct pl022_spi_slave *ps)
{
/* PL022 version is 0x00041022 */
if ((readw(ps->base + SSP_PID0) == 0x22) &&
(readw(ps->base + SSP_PID1) == 0x10) &&
((readw(ps->base + SSP_PID2) & 0xf) == 0x04) &&
(readw(ps->base + SSP_PID3) == 0x00))
return 1;
return 0;
}
#if !CONFIG_IS_ENABLED(OF_PLATDATA)
static int pl022_spi_ofdata_to_platdata(struct udevice *bus)
{
struct pl022_spi_pdata *plat = bus->platdata;
const void *fdt = gd->fdt_blob;
int node = dev_of_offset(bus);
plat->addr = fdtdec_get_addr_size(fdt, node, "reg", &plat->size);
return clk_get_by_index(bus, 0, &plat->clk);
}
#endif
static int pl022_spi_probe(struct udevice *bus)
{
struct pl022_spi_pdata *plat = dev_get_platdata(bus);
struct pl022_spi_slave *ps = dev_get_priv(bus);
ps->base = ioremap(plat->addr, plat->size);
#if !CONFIG_IS_ENABLED(OF_PLATDATA)
ps->clk = plat->clk;
#else
ps->freq = plat->freq;
#endif
/* Check the PL022 version */
if (!pl022_is_supported(ps))
return -ENOTSUPP;
/* 8 bits per word, high polarity and default clock rate */
writew(SSP_CR0_BIT_MODE(8), ps->base + SSP_CR0);
writew(DFLT_PRESCALE, ps->base + SSP_CPSR);
return 0;
}
static void flush(struct pl022_spi_slave *ps)
{
do {
while (readw(ps->base + SSP_SR) & SSP_SR_MASK_RNE)
readw(ps->base + SSP_DR);
} while (readw(ps->base + SSP_SR) & SSP_SR_MASK_BSY);
}
static int pl022_spi_claim_bus(struct udevice *dev)
{
struct udevice *bus = dev->parent;
struct pl022_spi_slave *ps = dev_get_priv(bus);
u16 reg;
/* Enable the SPI hardware */
reg = readw(ps->base + SSP_CR1);
reg |= SSP_CR1_MASK_SSE;
writew(reg, ps->base + SSP_CR1);
flush(ps);
return 0;
}
static int pl022_spi_release_bus(struct udevice *dev)
{
struct udevice *bus = dev->parent;
struct pl022_spi_slave *ps = dev_get_priv(bus);
u16 reg;
flush(ps);
/* Disable the SPI hardware */
reg = readw(ps->base + SSP_CR1);
reg &= ~SSP_CR1_MASK_SSE;
writew(reg, ps->base + SSP_CR1);
return 0;
}
static int pl022_spi_xfer(struct udevice *dev, unsigned int bitlen,
const void *dout, void *din, unsigned long flags)
{
struct udevice *bus = dev->parent;
struct pl022_spi_slave *ps = dev_get_priv(bus);
u32 len_tx = 0, len_rx = 0, len;
u32 ret = 0;
const u8 *txp = dout;
u8 *rxp = din, value;
if (bitlen == 0)
/* Finish any previously submitted transfers */
return 0;
/*
* TODO: The controller can do non-multiple-of-8 bit
* transfers, but this driver currently doesn't support it.
*
* It's also not clear how such transfers are supposed to be
* represented as a stream of bytes...this is a limitation of
* the current SPI interface.
*/
if (bitlen % 8) {
/* Errors always terminate an ongoing transfer */
flags |= SPI_XFER_END;
return -1;
}
len = bitlen / 8;
while (len_tx < len) {
if (readw(ps->base + SSP_SR) & SSP_SR_MASK_TNF) {
value = txp ? *txp++ : 0;
writew(value, ps->base + SSP_DR);
len_tx++;
}
if (readw(ps->base + SSP_SR) & SSP_SR_MASK_RNE) {
value = readw(ps->base + SSP_DR);
if (rxp)
*rxp++ = value;
len_rx++;
}
}
while (len_rx < len_tx) {
if (readw(ps->base + SSP_SR) & SSP_SR_MASK_RNE) {
value = readw(ps->base + SSP_DR);
if (rxp)
*rxp++ = value;
len_rx++;
}
}
return ret;
}
static inline u32 spi_rate(u32 rate, u16 cpsdvsr, u16 scr)
{
return rate / (cpsdvsr * (1 + scr));
}
static int pl022_spi_set_speed(struct udevice *bus, uint speed)
{
struct pl022_spi_slave *ps = dev_get_priv(bus);
u16 scr = SSP_SCR_MIN, cr0 = 0, cpsr = SSP_CPSR_MIN, best_scr = scr,
best_cpsr = cpsr;
u32 min, max, best_freq = 0, tmp;
#if !CONFIG_IS_ENABLED(OF_PLATDATA)
u32 rate = clk_get_rate(&ps->clk);
#else
u32 rate = ps->freq;
#endif
bool found = false;
max = spi_rate(rate, SSP_CPSR_MIN, SSP_SCR_MIN);
min = spi_rate(rate, SSP_CPSR_MAX, SSP_SCR_MAX);
if (speed > max || speed < min) {
pr_err("Tried to set speed to %dHz but min=%d and max=%d\n",
speed, min, max);
return -EINVAL;
}
while (cpsr <= SSP_CPSR_MAX && !found) {
while (scr <= SSP_SCR_MAX) {
tmp = spi_rate(rate, cpsr, scr);
if (abs(speed - tmp) < abs(speed - best_freq)) {
best_freq = tmp;
best_cpsr = cpsr;
best_scr = scr;
if (tmp == speed) {
found = true;
break;
}
}
scr++;
}
cpsr += 2;
scr = SSP_SCR_MIN;
}
writew(best_cpsr, ps->base + SSP_CPSR);
cr0 = readw(ps->base + SSP_CR0);
writew(cr0 | (best_scr << SSP_SCR_SHFT), ps->base + SSP_CR0);
return 0;
}
static int pl022_spi_set_mode(struct udevice *bus, uint mode)
{
struct pl022_spi_slave *ps = dev_get_priv(bus);
u16 reg;
reg = readw(ps->base + SSP_CR0);
reg &= ~(SSP_CR0_SPH | SSP_CR0_SPO);
if (mode & SPI_CPHA)
reg |= SSP_CR0_SPH;
if (mode & SPI_CPOL)
reg |= SSP_CR0_SPO;
writew(reg, ps->base + SSP_CR0);
return 0;
}
static int pl022_cs_info(struct udevice *bus, uint cs,
struct spi_cs_info *info)
{
return 0;
}
static const struct dm_spi_ops pl022_spi_ops = {
.claim_bus = pl022_spi_claim_bus,
.release_bus = pl022_spi_release_bus,
.xfer = pl022_spi_xfer,
.set_speed = pl022_spi_set_speed,
.set_mode = pl022_spi_set_mode,
.cs_info = pl022_cs_info,
};
#if !CONFIG_IS_ENABLED(OF_PLATDATA)
static const struct udevice_id pl022_spi_ids[] = {
{ .compatible = "arm,pl022-spi" },
{ }
};
#endif
U_BOOT_DRIVER(pl022_spi) = {
.name = "pl022_spi",
.id = UCLASS_SPI,
#if !CONFIG_IS_ENABLED(OF_PLATDATA)
.of_match = pl022_spi_ids,
#endif
.ops = &pl022_spi_ops,
#if !CONFIG_IS_ENABLED(OF_PLATDATA)
.ofdata_to_platdata = pl022_spi_ofdata_to_platdata,
#endif
.platdata_auto_alloc_size = sizeof(struct pl022_spi_pdata),
.priv_auto_alloc_size = sizeof(struct pl022_spi_slave),
.probe = pl022_spi_probe,
};