[PATCH v5 2/2] mtd: rawnand: meson: add support for Amlogic NAND flash controller

On 2018/10/19 4:39, Boris Brezillon wrote:

On Thu, 18 Oct 2018 13:09:05 +0800
Jianxin Pan [off-list ref] wrote:

quoted

+static int meson_nfc_calc_set_timing(struct meson_nfc *nfc,
+				     const struct nand_sdr_timings *timings)
+{
+	struct nand_timing *timing = &nfc->timing;
+	int div, bt_min, bt_max, bus_timing;
+	int ret;
+
+	div = DIV_ROUND_UP((timings->tRC_min / 1000), NFC_CLK_CYCLE);
+	ret = clk_set_rate(nfc->device_clk, 1000000000 / div);
+	if (ret) {
+		dev_err(nfc->dev, "failed to set nand clock rate\n");
+		return ret;
+	}
+
+	timing->twb = DIV_ROUND_UP(PSEC_TO_NSEC(timings->tWB_max),
+				   div * NFC_CLK_CYCLE);
+	timing->tadl = DIV_ROUND_UP(PSEC_TO_NSEC(timings->tADL_min),
+				    div * NFC_CLK_CYCLE);
+	timing->twhr = DIV_ROUND_UP(PSEC_TO_NSEC(timings->tWHR_min),
+				    div * NFC_CLK_CYCLE);
+
+	bt_min = (timings->tREA_max + NFC_DEFAULT_DELAY) / div;
+	bt_max = (NFC_DEFAULT_DELAY + timings->tRHOH_min
+			+ timings->tRC_min / 2) / div;
+
+	bt_min = DIV_ROUND_UP(bt_min, 1000);
+	bt_max = DIV_ROUND_UP(bt_max, 1000);
+
+	if (bt_max < bt_min)
+		return -EINVAL;
+
+	bus_timing = (bt_min + bt_max) / 2 + 1;
+
+	writel((1 << 21), nfc->reg_base + NFC_REG_CFG);
+	writel((NFC_CLK_CYCLE - 1) | (bus_timing << 5),
+	       nfc->reg_base + NFC_REG_CFG);
+
+	writel((1 << 31), nfc->reg_base + NFC_REG_CMD);
+
+	return 0;
+}
+
+static int
+meson_nfc_setup_data_interface(struct nand_chip *nand, int csline,
+			       const struct nand_data_interface *conf)
+{
+	struct meson_nfc *nfc = nand_get_controller_data(nand);
+	const struct nand_sdr_timings *timings;
+
+	timings = nand_get_sdr_timings(conf);
+	if (IS_ERR(timings))
+		return -ENOTSUPP;
+
+	if (csline == NAND_DATA_IFACE_CHECK_ONLY)
+		return 0;

Hm, before saying you supporting the requested timing, you should make
sure they are actually supported. I'd recommend splitting this in 2
steps:

1/ calc timings
2/ store the timings in the chip priv struct so that they can be
applied next time ->select_chip() is called.

ok, i will try to split.

quoted

+
+	meson_nfc_calc_set_timing(nfc, timings);
You should not set the timing from ->setup_data_interface(), just

calculate them, make sure they are supported and store the state in the
private chip struct. Applying those timings should be done in
->select_chip(), so that you can support 2 chips with different timings.

em, i will fix it.

quoted

+	return 0;
+}

.