[U-Boot] [PATCH v2] spi: Add SPI driver for MT76xx SoCs
Daniel Schwierzeck
daniel.schwierzeck at gmail.com
Wed Aug 15 12:02:27 UTC 2018
On 15.08.2018 13:26, Stefan Roese wrote:
> Hi Daniel,
>
> On 11.08.2018 18:59, Daniel Schwierzeck wrote:
>> On 10.08.2018 08:56, Stefan Roese wrote:
>>> This patch adds the SPI driver for the MediaTek MT7688 SoC (and
>>> derivates). Its been tested on the LinkIt Smart 7688 and the Gardena
>>> Smart Gateway with and SPI NOR on CS0 and on the Gardena Smart
>>> Gateway additionally with an SPI NAND on CS1.
>>>
>>> Note that the SPI controller only supports a max transfer size of 32
>>> bytes. This driver implementes a workaround to enable bigger xfer
>>> sizes to speed up the transfer especially for the SPI NAND support.
>>>
>>> Signed-off-by: Stefan Roese <sr at denx.de>
>>> Cc: Jagan Teki <jagan at openedev.com>
>>> ---
>>> v2:
>>> - Add some macros instead of hardcoded numbers
>>> - Move compatible DT struct down in the file
>>>
>>> drivers/spi/Kconfig | 8 +
>>> drivers/spi/Makefile | 1 +
>>> drivers/spi/mt76xx_spi.c | 319 +++++++++++++++++++++++++++++++++++++++
>>> 3 files changed, 328 insertions(+)
>>> create mode 100644 drivers/spi/mt76xx_spi.c
>>>
>>> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
>>> index 9fbd26740d..6c4e50d3e9 100644
>>> --- a/drivers/spi/Kconfig
>>> +++ b/drivers/spi/Kconfig
>>> @@ -116,6 +116,14 @@ config ICH_SPI
>>> access the SPI NOR flash on platforms embedding this Intel
>>> ICH IP core.
>>> +config MT76XX_SPI
>>> + bool "MediaTek MT76XX SPI driver"
>>> + depends on ARCH_MT7620
>>> + help
>>> + Enable the MT76XX SPI driver. This driver can be used to access
>>> + the SPI NOR flash on platforms embedding these MediaTek
>>> + SPI cores.
>>> +
>>> config MVEBU_A3700_SPI
>>> bool "Marvell Armada 3700 SPI driver"
>>> select CLK_ARMADA_3720
>>> diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
>>> index bdb5b5a02f..3d13ba1b21 100644
>>> --- a/drivers/spi/Makefile
>>> +++ b/drivers/spi/Makefile
>>> @@ -33,6 +33,7 @@ obj-$(CONFIG_KIRKWOOD_SPI) += kirkwood_spi.o
>>> obj-$(CONFIG_LPC32XX_SSP) += lpc32xx_ssp.o
>>> obj-$(CONFIG_MPC8XX_SPI) += mpc8xx_spi.o
>>> obj-$(CONFIG_MPC8XXX_SPI) += mpc8xxx_spi.o
>>> +obj-$(CONFIG_MT76XX_SPI) += mt76xx_spi.o
>>> obj-$(CONFIG_MVEBU_A3700_SPI) += mvebu_a3700_spi.o
>>> obj-$(CONFIG_MXC_SPI) += mxc_spi.o
>>> obj-$(CONFIG_MXS_SPI) += mxs_spi.o
>>> diff --git a/drivers/spi/mt76xx_spi.c b/drivers/spi/mt76xx_spi.c
>>> new file mode 100644
>>> index 0000000000..f26b5341ce
>>> --- /dev/null
>>> +++ b/drivers/spi/mt76xx_spi.c
>>> @@ -0,0 +1,319 @@
>>> +// SPDX-License-Identifier: GPL-2.0+
>>> +/*
>>> + * Copyright (C) 2018 Stefan Roese <sr at denx.de>
>>> + *
>>> + * Derived from the Linux driver version drivers/spi/spi-mt7621.c
>>> + * Copyright (C) 2011 Sergiy <piratfm at gmail.com>
>>> + * Copyright (C) 2011-2013 Gabor Juhos <juhosg at openwrt.org>
>>> + * Copyright (C) 2014-2015 Felix Fietkau <nbd at nbd.name>
>>> + */
>>> +
>>> +#include <common.h>
>>> +#include <dm.h>
>>> +#include <spi.h>
>>> +#include <wait_bit.h>
>>> +#include <linux/io.h>
>>> +
>>> +#define SPI_MSG_SIZE_MAX 32 /* SPI message chunk size */
>>> +/* Enough for SPI NAND page read / write with page size 2048 bytes */
>>> +#define SPI_MSG_SIZE_OVERALL (2048 + 16)
>>> +
>>> +#define MT7621_SPI_TRANS 0x00
>>> +#define MT7621_SPI_TRANS_START BIT(8)
>>> +#define MT7621_SPI_TRANS_BUSY BIT(16)
>>> +
>>> +#define MT7621_SPI_OPCODE 0x04
>>> +#define MT7621_SPI_DATA0 0x08
>>> +#define MT7621_SPI_DATA4 0x18
>>> +#define MT7621_SPI_MASTER 0x28
>>> +#define MT7621_SPI_MOREBUF 0x2c
>>> +#define MT7621_SPI_POLAR 0x38
>>> +
>>> +#define MT7621_LSB_FIRST BIT(3)
>>> +#define MT7621_CPOL BIT(4)
>>> +#define MT7621_CPHA BIT(5)
>>> +
>>> +#define MASTER_MORE_BUFMODE BIT(2)
>>> +#define MASTER_RS_CLK_SEL GENMASK(27, 16)
>>> +#define MASTER_RS_CLK_SEL_SHIFT 16
>>> +#define MASTER_RS_SLAVE_SEL GENMASK(31, 29)
>>> +
>>> +struct mt7621_spi {
>>> + void __iomem *base;
>>> + unsigned int sys_freq;
>>> + u32 data[(SPI_MSG_SIZE_OVERALL / 4) + 1];
>>> + int tx_len;
>>> +};
>>> +
>>> +static inline u32 mt7621_spi_read(struct mt7621_spi *rs, u32 reg)
>>> +{
>>> + return ioread32(rs->base + reg);
>>> +}
>>> +
>>> +static inline void mt7621_spi_write(struct mt7621_spi *rs, u32 reg,
>>> u32 val)
>>> +{
>>> + iowrite32(val, rs->base + reg);
>>> +}
>>> +
>>> +static void mt7621_spi_reset(struct mt7621_spi *rs, int duplex)
>>> +{
>>> + u32 master = mt7621_spi_read(rs, MT7621_SPI_MASTER);
>>> +
>>> + master |= MASTER_RS_SLAVE_SEL; /* CS control */
>>> + master |= MASTER_MORE_BUFMODE; /* more_buf_mode */
>>> +
>>> + mt7621_spi_write(rs, MT7621_SPI_MASTER, master);
>>
>> if you omit the (actually unneeded) I/O wrappers, you could simplify
>> this with setbits_le32() (or setbits_32() for non-enforcing endianess)
>
> Yes, you are correct. All this is derived / copied from the Linux
> driver. Even though the main xfer routine is pretty much different,
> so it makes not much sense any more to stick with this IO wrappers
> for code compatibility.
>
> I could work on a new version of this driver, omitting these IO
> wrappers, if this is preferred. Or I could do this in a follow-up
> patch, once this one is in mainline (time is a bit short right now).
follow-up patch would be ok, it was only meant as optional improvement.
But maybe the mt7621_ prefix could be replaced with mt76xx_ to be
consistent with the source file name?
>
>>> +}
>>> +
>>> +static void mt7621_spi_set_cs(struct mt7621_spi *rs, int cs, int
>>> enable)
>>> +{
>>> + u32 val = 0;
>>> +
>>> + debug("%s: cs#%d -> %s\n", __func__, cs, enable ? "enable" :
>>> "disable");
>>> + if (enable)
>>> + val = BIT(cs);
>>> + mt7621_spi_write(rs, MT7621_SPI_POLAR, val);
>>> +}
>>> +
>>> +static int mt7621_spi_set_mode(struct udevice *bus, uint mode)
>>> +{
>>> + struct mt7621_spi *rs = dev_get_priv(bus);
>>> + u32 reg;
>>> +
>>> + debug("%s: mode=0x%08x\n", __func__, mode);
>>> + reg = mt7621_spi_read(rs, MT7621_SPI_MASTER);
>>> +
>>> + reg &= ~MT7621_LSB_FIRST;
>>> + if (mode & SPI_LSB_FIRST)
>>> + reg |= MT7621_LSB_FIRST;
>>> +
>>> + reg &= ~(MT7621_CPHA | MT7621_CPOL);
>>> + switch (mode & (SPI_CPOL | SPI_CPHA)) {
>>> + case SPI_MODE_0:
>>> + break;
>>> + case SPI_MODE_1:
>>> + reg |= MT7621_CPHA;
>>> + break;
>>> + case SPI_MODE_2:
>>> + reg |= MT7621_CPOL;
>>> + break;
>>> + case SPI_MODE_3:
>>> + reg |= MT7621_CPOL | MT7621_CPHA;
>>> + break;
>>> + }
>>> + mt7621_spi_write(rs, MT7621_SPI_MASTER, reg);
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static int mt7621_spi_set_speed(struct udevice *bus, uint speed)
>>> +{
>>> + struct mt7621_spi *rs = dev_get_priv(bus);
>>> + u32 rate;
>>> + u32 reg;
>>> +
>>> + debug("%s: speed=%d\n", __func__, speed);
>>> + rate = DIV_ROUND_UP(rs->sys_freq, speed);
>>> + debug("rate:%u\n", rate);
>>> +
>>> + if (rate > 4097)
>>> + return -EINVAL;
>>> +
>>> + if (rate < 2)
>>> + rate = 2;
>>> +
>>> + reg = mt7621_spi_read(rs, MT7621_SPI_MASTER);
>>> + reg &= ~MASTER_RS_CLK_SEL;
>>> + reg |= (rate - 2) << MASTER_RS_CLK_SEL_SHIFT;
>>> + mt7621_spi_write(rs, MT7621_SPI_MASTER, reg);
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static inline int mt7621_spi_wait_till_ready(struct mt7621_spi *rs)
>>> +{
>>> + int ret;
>>> +
>>> + ret = wait_for_bit_le32(rs->base + MT7621_SPI_TRANS,
>>> + MT7621_SPI_TRANS_BUSY, 0, 10, 0);
>>> + if (ret)
>>> + pr_err("Timeout in %s!\n", __func__);
>>> +
>>> + return ret;
>>> +}
>>> +
>>> +static int mt7621_spi_xfer(struct udevice *dev, unsigned int bitlen,
>>> + const void *dout, void *din, unsigned long flags)
>>> +{
>>> + struct udevice *bus = dev->parent;
>>> + struct mt7621_spi *rs = dev_get_priv(bus);
>>> + const u8 *tx_buf = dout;
>>> + u8 *ptr = (u8 *)dout;
>>> + u8 *rx_buf = din;
>>> + int total_size = bitlen >> 3;
>>> + int chunk_size;
>>> + int rx_len = 0;
>>> + u32 data[(SPI_MSG_SIZE_MAX / 4) + 1] = { 0 };
>>> + u32 val;
>>> + int i;
>>> +
>>> + debug("%s: dout=%p, din=%p, len=%x, flags=%lx\n", __func__,
>>> dout, din,
>>> + total_size, flags);
>>> +
>>> + /*
>>> + * This driver only supports half-duplex, so complain and bail out
>>> + * upon full-duplex messages
>>> + */
>>> + if (dout && din) {
>>> + printf("Only half-duplex SPI transfer supported\n");
>>> + return -EIO;
>>> + }
>>> +
>>> + if (dout) {
>>> + debug("TX-DATA: ");
>>> + for (i = 0; i < total_size; i++)
>>> + debug("%02x ", *ptr++);
>>> + debug("\n");
>>> + }
>>> +
>>> + mt7621_spi_wait_till_ready(rs);
>>> +
>>> + /*
>>> + * Set CS active upon start of SPI message. This message can
>>> + * be split upon multiple calls to this xfer function
>>> + */
>>> + if (flags & SPI_XFER_BEGIN)
>>> + mt7621_spi_set_cs(rs, spi_chip_select(dev), 1);
>>> +
>>> + while (total_size > 0) {
>>> + /* Don't exceed the max xfer size */
>>> + chunk_size = min_t(int, total_size, SPI_MSG_SIZE_MAX);
>>> +
>>> + /*
>>> + * We might have some TX data buffered from the last xfer
>>> + * message. Make sure, that this does not exceed the max
>>> + * xfer size
>>> + */
>>> + if (rs->tx_len > 4)
>>> + chunk_size -= rs->tx_len;
>>> + if (din)
>>> + rx_len = chunk_size;
>>> +
>>> + if (tx_buf) {
>>> + /* Check if this message does not exceed the buffer */
>>> + if ((chunk_size + rs->tx_len) > SPI_MSG_SIZE_OVERALL) {
>>> + printf("TX message size too big (%d)\n",
>>> + chunk_size + rs->tx_len);
>>> + return -EMSGSIZE;
>>> + }
>>> +
>>> + /*
>>> + * Write all TX data into internal buffer to collect
>>> + * all TX messages into one buffer (might be split into
>>> + * multiple calls to this function)
>>> + */
>>> + for (i = 0; i < chunk_size; i++, rs->tx_len++) {
>>> + rs->data[rs->tx_len / 4] |=
>>> + tx_buf[i] << (8 * (rs->tx_len & 3));
>>> + }
>>> + }
>>> +
>>> + if (flags & SPI_XFER_END) {
>>> + /* Write TX data into controller */
>>> + if (rs->tx_len) {
>>> + rs->data[0] = swab32(rs->data[0]);
>>> + if (rs->tx_len < 4)
>>> + rs->data[0] >>= (4 - rs->tx_len) * 8;
>>> +
>>> + for (i = 0; i < rs->tx_len; i += 4) {
>>> + mt7621_spi_write(rs,
>>> + MT7621_SPI_OPCODE + i,
>>> + rs->data[i / 4]);
>>> + }
>>> + }
>>> +
>>> + /* Write length into controller */
>>> + val = (min_t(int, rs->tx_len, 4) * 8) << 24;
>>> + if (rs->tx_len > 4)
>>> + val |= (rs->tx_len - 4) * 8;
>>> + val |= (rx_len * 8) << 12;
>>> + mt7621_spi_write(rs, MT7621_SPI_MOREBUF, val);
>>> +
>>> + /* Start the xfer */
>>> + val = mt7621_spi_read(rs, MT7621_SPI_TRANS);
>>> + val |= MT7621_SPI_TRANS_START;
>>> + mt7621_spi_write(rs, MT7621_SPI_TRANS, val);
>>> +
>>> + /* Wait until xfer is finished on bus */
>>> + mt7621_spi_wait_till_ready(rs);
>>> +
>>> + /* Reset TX length and TX buffer for next xfer */
>>> + rs->tx_len = 0;
>>> + memset(rs->data, 0, sizeof(rs->data));
>>> + }
>>> +
>>> + for (i = 0; i < rx_len; i += 4)
>>> + data[i / 4] = mt7621_spi_read(rs, MT7621_SPI_DATA0 + i);
>>> +
>>> + if (rx_len) {
>>> + debug("RX-DATA: ");
>>> + for (i = 0; i < rx_len; i++) {
>>> + rx_buf[i] = data[i / 4] >> (8 * (i & 3));
>>> + debug("%02x ", rx_buf[i]);
>>> + }
>>> + debug("\n");
>>> + }
>>> +
>>> + if (tx_buf)
>>> + tx_buf += chunk_size;
>>> + if (rx_buf)
>>> + rx_buf += chunk_size;
>>> + total_size -= chunk_size;
>>> + }
>>> +
>>> + /* Wait until xfer is finished on bus and de-assert CS */
>>> + mt7621_spi_wait_till_ready(rs);
>>> + if (flags & SPI_XFER_END)
>>> + mt7621_spi_set_cs(rs, spi_chip_select(dev), 0);
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static int mt76xx_spi_probe(struct udevice *dev)
>>> +{
>>> + struct mt7621_spi *rs = dev_get_priv(dev);
>>> +
>>> + rs->base = dev_remap_addr(dev);
>>> + if (!rs->base)
>>> + return -EINVAL;
>>> +
>>> + rs->sys_freq = CONFIG_SYS_MIPS_TIMER_FREQ;
>>
>> you should create a minimal clock driver based on the system controller
>> block. The SPI clock has a separate bit for clock gating, so at least
>> one driver has to take care of enabling that clock. Also using
>> CONFIG_SYS_MIPS_TIMER_FREQ is a bad choice because it is a hard-coded
>> value which is usually the CPU clock divided by two. But CPU clock and
>> SYS clock are derived from PLL clock and can be configured with
>> different dividers.
>
> Yes, this all sounds like a good idea. Unfortunately this work is not
> trivial, as (at least to my knowledge) no such clock driver exist
> in Linux right now. Documentation for the MT7688 is also very "limited"
> and the Linux DT has no clock nodes at all.
>
> As time is very limited right now for such "improvements", would it
> be acceptable to add such a minimal clock driver at a later time?
>
> Thanks,
> Stefan
ok, but at least use a DT property for the clock frequency or use a
fixed-clock driver, e.g.
spi_clk: spi-clk {
compatible = "fixed-clock";
#clock-cells = <0>;
clock-frequency = <3000000>;
u-boot,dm-pre-reloc;
};
--
- Daniel
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