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SubjectRe: [PATCH v2 2/2] mtd: spi-nor: add driver for STM32 quad spi flash controller
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On 04/10/2017 11:08 AM, Ludovic BARRE wrote:
>
> On 04/07/2017 01:55 AM, Marek Vasut wrote:
>> On 03/31/2017 07:02 PM, Ludovic Barre wrote:
>>> From: Ludovic Barre <ludovic.barre@st.com>
>>>
>>> The quadspi is a specialized communication interface targeting single,
>>> dual or quad SPI Flash memories.
>>>
>>> It can operate in any of the following modes:
>>> -indirect mode: all the operations are performed using the quadspi
>>> registers
>>> -read memory-mapped mode: the external Flash memory is mapped to the
>>> microcontroller address space and is seen by the system as if it was
>>> an internal memory
>>>
>>> Signed-off-by: Ludovic Barre <ludovic.barre@st.com>
>>> ---
>>> drivers/mtd/spi-nor/Kconfig | 7 +
>>> drivers/mtd/spi-nor/Makefile | 1 +
>>> drivers/mtd/spi-nor/stm32-quadspi.c | 690
>>> ++++++++++++++++++++++++++++++++++++
>>> 3 files changed, 698 insertions(+)
>>> create mode 100644 drivers/mtd/spi-nor/stm32-quadspi.c
>>>
>> [...]
>>
>>> +struct stm32_qspi_flash {
>>> + struct spi_nor nor;
>>> + u32 cs;
>>> + u32 fsize;
>>> + u32 presc;
>>> + struct stm32_qspi *qspi;
>>> +};
>> [...]
>>
>>> +struct stm32_qspi_cmd {
>>> + struct {
>>> + u8 addr_width;
>>> + u8 dummy;
>>> + u8 data;
>>> + } conf;
>> Is there any benefit in having this structure here or could you just
>> make the struct stm32_qspi_cmd flat ?
> no benefit, it was just to regroup, so I can do a flat structure

Well, as you like, but I think it does make sense to just make it flat.

>>> + u8 opcode;
>>> + u32 framemode;
>>> + u32 qspimode;
>>> + u32 addr;
>>> + size_t len;
>>> + void *buf;
>>> +};
>> [...]
>>
>>> +static ssize_t stm32_qspi_read(struct spi_nor *nor, loff_t from,
>>> size_t len,
>>> + u_char *buf)
>>> +{
>>> + struct stm32_qspi_flash *flash = nor->priv;
>>> + struct stm32_qspi *qspi = flash->qspi;
>>> + struct stm32_qspi_cmd cmd;
>>> + int err;
>>> +
>>> + dev_dbg(qspi->dev, "read(%#.2x): buf:%p from:%#.8x len:%#x\n",
>>> + nor->read_opcode, buf, (u32)from, len);
>>> +
>>> + memset(&cmd, 0, sizeof(cmd));
>>> + cmd.opcode = nor->read_opcode;
>>> + cmd.conf.addr_width = nor->addr_width;
>>> + cmd.addr = (u32)from;
>> loff_t (from) can be 64bit ... how do we handle this ?
> I'm surprise by the question,
> the SPI NOR device uses 3 Bytes or 4 bytes address mode.
> So, the stm32 qspi controller has a 32 bit register for NOR address.
> On the other hand the framework and other drivers used this variable
> (from) like
> a 32 bits.

Hmmm, (rhetorical question) then why do we even use loff_t in the
framework ?

Anyway, this is no problem then.

>>> + cmd.conf.data = 1;
>>> + cmd.conf.dummy = nor->read_dummy;
>>> + cmd.len = len;
>>> + cmd.buf = buf;
>>> + cmd.qspimode = qspi->read_mode;
>>> +
>>> + stm32_qspi_set_framemode(nor, &cmd, true);
>>> + err = stm32_qspi_send(flash, &cmd);
>>> +
>>> + return err ? err : len;
>>> +}
>> [...]
>>
>>> +static irqreturn_t stm32_qspi_irq(int irq, void *dev_id)
>>> +{
>>> + struct stm32_qspi *qspi = (struct stm32_qspi *)dev_id;
>>> + u32 cr, sr, fcr = 0;
>>> +
>>> + cr = readl_relaxed(qspi->io_base + QUADSPI_CR);
>>> + sr = readl_relaxed(qspi->io_base + QUADSPI_SR);
>>> +
>>> + if ((cr & CR_TCIE) && (sr & SR_TCF)) {
>>> + /* tx complete */
>>> + fcr |= FCR_CTCF;
>>> + complete(&qspi->cmd_completion);
>>> + } else {
>>> + dev_info(qspi->dev, "spurious interrupt\n");
>> You probably want to ratelimit this one ...
> yes it's better if there is an issue.

Yep

>>> + }
>>> +
>>> + writel_relaxed(fcr, qspi->io_base + QUADSPI_FCR);
>>> +
>>> + return IRQ_HANDLED;
>>> +}
>>> +
>>> +static int stm32_qspi_prep(struct spi_nor *nor, enum spi_nor_ops ops)
>>> +{
>>> + struct stm32_qspi_flash *flash = nor->priv;
>>> + struct stm32_qspi *qspi = flash->qspi;
>>> +
>>> + mutex_lock(&qspi->lock);
>>> + return 0;
>>> +}
>>> +
>>> +static void stm32_qspi_unprep(struct spi_nor *nor, enum spi_nor_ops
>>> ops)
>>> +{
>>> + struct stm32_qspi_flash *flash = nor->priv;
>>> + struct stm32_qspi *qspi = flash->qspi;
>>> +
>>> + mutex_unlock(&qspi->lock);
>>> +}
>>> +
>>> +static int stm32_qspi_flash_setup(struct stm32_qspi *qspi,
>>> + struct device_node *np)
>>> +{
>>> + u32 width, flash_read, presc, cs_num, max_rate = 0;
>>> + struct stm32_qspi_flash *flash;
>>> + struct mtd_info *mtd;
>>> + int ret;
>>> +
>>> + of_property_read_u32(np, "reg", &cs_num);
>>> + if (cs_num >= STM32_MAX_NORCHIP)
>>> + return -EINVAL;
>>> +
>>> + of_property_read_u32(np, "spi-max-frequency", &max_rate);
>>> + if (!max_rate)
>>> + return -EINVAL;
>>> +
>>> + presc = DIV_ROUND_UP(qspi->clk_rate, max_rate) - 1;
>>> +
>>> + if (of_property_read_u32(np, "spi-rx-bus-width", &width))
>>> + width = 1;
>>> +
>>> + if (width == 4)
>>> + flash_read = SPI_NOR_QUAD;
>>> + else if (width == 2)
>>> + flash_read = SPI_NOR_DUAL;
>>> + else if (width == 1)
>>> + flash_read = SPI_NOR_NORMAL;
>>> + else
>>> + return -EINVAL;
>>> +
>>> + flash = &qspi->flash[cs_num];
>>> + flash->qspi = qspi;
>>> + flash->cs = cs_num;
>>> + flash->presc = presc;
>>> +
>>> + flash->nor.dev = qspi->dev;
>>> + spi_nor_set_flash_node(&flash->nor, np);
>>> + flash->nor.priv = flash;
>>> + mtd = &flash->nor.mtd;
>>> + mtd->priv = &flash->nor;
>>> +
>>> + flash->nor.read = stm32_qspi_read;
>>> + flash->nor.write = stm32_qspi_write;
>>> + flash->nor.erase = stm32_qspi_erase;
>>> + flash->nor.read_reg = stm32_qspi_read_reg;
>>> + flash->nor.write_reg = stm32_qspi_write_reg;
>>> + flash->nor.prepare = stm32_qspi_prep;
>>> + flash->nor.unprepare = stm32_qspi_unprep;
>>> +
>>> + writel_relaxed(LPTR_DFT_TIMEOUT, qspi->io_base + QUADSPI_LPTR);
>>> +
>>> + writel_relaxed(CR_PRESC(presc) | CR_FTHRES(3) | CR_TCEN | CR_SSHIFT
>>> + | CR_EN, qspi->io_base + QUADSPI_CR);
>>> +
>>> + /*
>>> + * in stm32 qspi controller, QUADSPI_DCR register has a fsize field
>>> + * which define the size of nor flash.
>>> + * if fsize is NULL, the controller can't sent spi-nor command.
>>> + * set a temporary value just to discover the nor flash with
>>> + * "spi_nor_scan". After, the right value (mtd->size) can be set.
>>> + */
>> Is 25 the smallest value ? Use a macro for this ...
> 25 is an arbitrary choice, I will define a smallest value

Cool, thanks!

--
Best regards,
Marek Vasut

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