Re: [PATCH 2/2] mtd: spi-nor: add driver for STM32 quad spi flash controller
From: Ludovic BARRE
Date: Wed Mar 29 2017 - 09:36:56 EST
On 03/29/2017 03:09 PM, Marek Vasut wrote:
On 03/29/2017 02:24 PM, Ludovic BARRE wrote:
hi Marek
Hi!
thanks for review
comment below
On 03/29/2017 12:54 PM, Marek Vasut wrote:
On 03/27/2017 02:54 PM, Ludovic Barre wrote:
From: Ludovic Barre <ludovic.barre@xxxxxx>
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@xxxxxx>
Hi! I presume this is not compatible with the Cadence QSPI or any other
QSPI controller, huh ?
it's not a cadence QSPI, it's specific for stm32 platform
OK, got it. Didn't ST use Cadence IP somewhere too though ?
That's probably what confused me, oh well ...
Mostly minor nits below ...
---
drivers/mtd/spi-nor/Kconfig | 7 +
drivers/mtd/spi-nor/Makefile | 1 +
drivers/mtd/spi-nor/stm32-quadspi.c | 679
++++++++++++++++++++++++++++++++++++
3 files changed, 687 insertions(+)
create mode 100644 drivers/mtd/spi-nor/stm32-quadspi.c
[...]
+struct stm32_qspi_cmd {
+ struct {
+ u32 addr_width:8;
+ u32 dummy:8;
+ u32 data:1;
+ } conf;
This could all be u8 ? Why this awful construct ?
yes I could replace each u32 by u8
Yeah, please do .
+ u8 opcode;
+ u32 framemode;
+ u32 qspimode;
+ u32 addr;
+ size_t len;
+ void *buf;
+};
+
+static int stm32_qspi_wait_cmd(struct stm32_qspi *qspi)
+{
+ u32 cr;
+ int err = 0;
Can readl_poll_timeout() or somesuch replace this function ?
in fact stm32_qspi_wait_cmd test if the transfer has been complete (TCF
flag)
else initialize an interrupt completion.
like the time may be long I prefer keep the interrupt wait, if you agree.
I don't really mind if it fits the hardware better and I agree with you
it does here.
+ if (readl_relaxed(qspi->io_base + QUADSPI_SR) & SR_TCF)
+ return 0;
+
+ reinit_completion(&qspi->cmd_completion);
+ cr = readl_relaxed(qspi->io_base + QUADSPI_CR);
+ writel_relaxed(cr | CR_TCIE, qspi->io_base + QUADSPI_CR);
+
+ if
(!wait_for_completion_interruptible_timeout(&qspi->cmd_completion,
+ msecs_to_jiffies(1000)))
+ err = -ETIMEDOUT;
+
+ writel_relaxed(cr, qspi->io_base + QUADSPI_CR);
+ return err;
+}
+
+static int stm32_qspi_wait_nobusy(struct stm32_qspi *qspi)
+{
+ u32 sr;
+
+ return readl_relaxed_poll_timeout(qspi->io_base + QUADSPI_SR, sr,
+ !(sr & SR_BUSY), 10, 100000);
+}
+
+static void stm32_qspi_set_framemode(struct spi_nor *nor,
+ struct stm32_qspi_cmd *cmd, bool read)
+{
+ u32 dmode = CCR_DMODE_1;
+
+ cmd->framemode = CCR_IMODE_1;
+
+ if (read) {
+ switch (nor->flash_read) {
+ case SPI_NOR_NORMAL:
+ case SPI_NOR_FAST:
+ dmode = CCR_DMODE_1;
+ break;
+ case SPI_NOR_DUAL:
+ dmode = CCR_DMODE_2;
+ break;
+ case SPI_NOR_QUAD:
+ dmode = CCR_DMODE_4;
+ break;
+ }
+ }
+
+ cmd->framemode |= cmd->conf.data ? dmode : 0;
+ cmd->framemode |= cmd->conf.addr_width ? CCR_ADMODE_1 : 0;
+}
+
+static void stm32_qspi_read_fifo(u8 *val, void __iomem *addr)
+{
+ *val = readb_relaxed(addr);
+}
+
+static void stm32_qspi_write_fifo(u8 *val, void __iomem *addr)
+{
+ writeb_relaxed(*val, addr);
+}
+
+static int stm32_qspi_tx_poll(struct stm32_qspi *qspi,
+ const struct stm32_qspi_cmd *cmd)
+{
+ void (*tx_fifo)(u8 *, void __iomem *);
+ u32 len = cmd->len, sr;
+ u8 *buf = cmd->buf;
+ int ret;
+
+ if (cmd->qspimode == CCR_FMODE_INDW)
+ tx_fifo = stm32_qspi_write_fifo;
+ else
+ tx_fifo = stm32_qspi_read_fifo;
+
+ while (len--) {
+ ret = readl_relaxed_poll_timeout(qspi->io_base + QUADSPI_SR,
+ sr, (sr & SR_FTF),
+ 10, 30000);
Add macros for those ad-hoc timeouts.
I will add 2 defines (for stm32_qspi_wait_nobusy, stm32_qspi_tx_poll)
#define STM32_QSPI_FIFO_TIMEOUT_US 30000
#define STM32_QSPI_BUSY_TIMEOUT_US 100000
Super
+ if (ret) {
+ dev_err(qspi->dev, "fifo timeout (stat:%#x)\n", sr);
+ break;
+ }
+ tx_fifo(buf++, qspi->io_base + QUADSPI_DR);
+ }
+
+ return ret;
+}
[...]
+static int stm32_qspi_send(struct stm32_qspi_flash *flash,
+ const struct stm32_qspi_cmd *cmd)
+{
+ struct stm32_qspi *qspi = flash->qspi;
+ u32 ccr, dcr, cr;
+ int err;
+
+ err = stm32_qspi_wait_nobusy(qspi);
+ if (err)
+ goto abort;
+
+ dcr = readl_relaxed(qspi->io_base + QUADSPI_DCR) & ~DCR_FSIZE_MASK;
+ dcr |= DCR_FSIZE(flash->fsize);
+ writel_relaxed(dcr, qspi->io_base + QUADSPI_DCR);
+
+ cr = readl_relaxed(qspi->io_base + QUADSPI_CR);
+ cr &= ~CR_PRESC_MASK & ~CR_FSEL;
+ cr |= CR_PRESC(flash->presc);
+ cr |= flash->cs ? CR_FSEL : 0;
+ writel_relaxed(cr, qspi->io_base + QUADSPI_CR);
+
+ if (cmd->conf.data)
+ writel_relaxed(cmd->len - 1, qspi->io_base + QUADSPI_DLR);
+
+ ccr = cmd->framemode | cmd->qspimode;
+
+ if (cmd->conf.dummy)
+ ccr |= CCR_DCYC(cmd->conf.dummy);
+
+ if (cmd->conf.addr_width)
+ ccr |= CCR_ADSIZE(cmd->conf.addr_width - 1);
+
+ ccr |= CCR_INST(cmd->opcode);
+ writel_relaxed(ccr, qspi->io_base + QUADSPI_CCR);
+
+ if (cmd->conf.addr_width && cmd->qspimode != CCR_FMODE_MM)
+ writel_relaxed(cmd->addr, qspi->io_base + QUADSPI_AR);
+
+ err = stm32_qspi_tx(qspi, cmd);
+ if (err)
+ goto abort;
+
+ if (cmd->qspimode != CCR_FMODE_MM) {
+ err = stm32_qspi_wait_cmd(qspi);
+ if (err)
+ goto abort;
+ writel_relaxed(FCR_CTCF, qspi->io_base + QUADSPI_FCR);
+ }
+
+ return err;
+
+abort:
+ writel_relaxed(readl_relaxed(qspi->io_base + QUADSPI_CR)
+ | CR_ABORT, qspi->io_base + QUADSPI_CR);
Use a helper variable here too.
ok
+ dev_err(qspi->dev, "%s abort err:%d\n", __func__, err);
+ return err;
+}
[...]
+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);
+
+ /* a minimum fsize must be set to sent the command id */
+ flash->fsize = 25;
I don't understand why this is needed and the comment doesn't make
sense. Please fix.
fsize field defines the size of external memory.
What external memory ? Unclear
oops, fsize field defined the size of "flash memory" in stm32 qspi
controller.
Number of bytes in Flash memory = 2 ^[FSIZE+1].
To sent a nor cmd this field must be set (hardware issue),
but before "spi_nor_scan" the size of flash nor is not know.
So I set a temporary value (workaround).
After "spi_nor_scan" the fsize is overwritten by the right value
flash->fsize = __fls(mtd->size) - 1;
Normaly, this field is used only for memory map mode,
but in fact is check in indirect mode.
So while flash scan "spi_nor_scan":
-I can't let 0.
-I not know yet the size of flash.
So I fix a temporary value
I will update my comment
Please do, also please consider that I'm reading the comment and I
barely have any clue about this hardware , so make sure I can understand it.
+ ret = spi_nor_scan(&flash->nor, NULL, flash_read);
+ if (ret) {
+ dev_err(qspi->dev, "device scan failed\n");
+ return ret;
+ }
+
+ flash->fsize = __fls(mtd->size) - 1;
+
+ writel_relaxed(DCR_CSHT(1), qspi->io_base + QUADSPI_DCR);
+
+ ret = mtd_device_register(mtd, NULL, 0);
+ if (ret) {
+ dev_err(qspi->dev, "mtd device parse failed\n");
+ return ret;
+ }
+
+ dev_dbg(qspi->dev, "read mm:%s cs:%d bus:%d\n",
+ qspi->read_mode == CCR_FMODE_MM ? "yes" : "no", cs_num, width);
+
+ return 0;
+}
[...]