Re: [PATCH v2 2/2] mtd: spi-nor: add driver for STM32 quad spi flash controller
From: Ludovic BARRE
Date: Mon Apr 10 2017 - 12:55:29 EST
hi Marek
tomorrow, I send a v3 with your/Rob reviews.
BR
Ludo
On 04/10/2017 06:15 PM, Marek Vasut wrote:
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@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>
---
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.
In fact, the loff_t 64 bit come from mtd interface
(needed to address biggest device constraint) but not needed for spi-nor
devices.
+ 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!