mtd: nand: mxc: Add timing setup for v2 controllers

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=8283079696aba905367297cf80287980eb34c14c
Commit:     8283079696aba905367297cf80287980eb34c14c
Parent:     4123ea34aac754cdbd0a5e482c29be433c311d67
Author:     Sascha Hauer <s.hauer at pengutronix.de>
AuthorDate: Thu Sep 15 10:32:53 2016 +0200
Committer:  Boris Brezillon <boris.brezillon at free-electrons.com>
CommitDate: Fri Sep 23 09:35:16 2016 +0200

    mtd: nand: mxc: Add timing setup for v2 controllers
    
    So far we relied on reset default or the bootloader to configure a
    suitable clk rate for the Nand controller. This works but we can
    optimize the timing for better performance. This sets the clk rate for
    v2 controllers (i.MX25/35) based on the timing mode read from the ONFI
    parameter page. This may also enable the symmetric mode (aks EDO mode)
    if necessary which reads one word per clock cycle.
    Tested on an i.MX25 with a Micron MT29F4G08ABBDAHC attached.
    
    Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
    Signed-off-by: Boris Brezillon <boris.brezillon at free-electrons.com>
---
 drivers/mtd/nand/mxc_nand.c | 84 +++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 82 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/mxc_nand.c b/drivers/mtd/nand/mxc_nand.c
index 8bd8108..75c0c0e 100644
--- a/drivers/mtd/nand/mxc_nand.c
+++ b/drivers/mtd/nand/mxc_nand.c
@@ -152,6 +152,9 @@ struct mxc_nand_devtype_data {
 	void (*select_chip)(struct mtd_info *mtd, int chip);
 	int (*correct_data)(struct mtd_info *mtd, u_char *dat,
 			u_char *read_ecc, u_char *calc_ecc);
+	int (*setup_data_interface)(struct mtd_info *mtd,
+				    const struct nand_data_interface *conf,
+				    bool check_only);
 
 	/*
 	 * On i.MX21 the CONFIG2:INT bit cannot be read if interrupts are masked
@@ -1012,6 +1015,82 @@ static void preset_v1(struct mtd_info *mtd)
 	writew(0x4, NFC_V1_V2_WRPROT);
 }
 
+static int mxc_nand_v2_setup_data_interface(struct mtd_info *mtd,
+					const struct nand_data_interface *conf,
+					bool check_only)
+{
+	struct nand_chip *nand_chip = mtd_to_nand(mtd);
+	struct mxc_nand_host *host = nand_get_controller_data(nand_chip);
+	int tRC_min_ns, tRC_ps, ret;
+	unsigned long rate, rate_round;
+	const struct nand_sdr_timings *timings;
+	u16 config1;
+
+	timings = nand_get_sdr_timings(conf);
+	if (IS_ERR(timings))
+		return -ENOTSUPP;
+
+	config1 = readw(NFC_V1_V2_CONFIG1);
+
+	tRC_min_ns = timings->tRC_min / 1000;
+	rate = 1000000000 / tRC_min_ns;
+
+	/*
+	 * For tRC < 30ns we have to use EDO mode. In this case the controller
+	 * does one access per clock cycle. Otherwise the controller does one
+	 * access in two clock cycles, thus we have to double the rate to the
+	 * controller.
+	 */
+	if (tRC_min_ns < 30) {
+		rate_round = clk_round_rate(host->clk, rate);
+		config1 |= NFC_V2_CONFIG1_ONE_CYCLE;
+		tRC_ps = 1000000000 / (rate_round / 1000);
+	} else {
+		rate *= 2;
+		rate_round = clk_round_rate(host->clk, rate);
+		config1 &= ~NFC_V2_CONFIG1_ONE_CYCLE;
+		tRC_ps = 1000000000 / (rate_round / 1000 / 2);
+	}
+
+	/*
+	 * The timing values compared against are from the i.MX25 Automotive
+	 * datasheet, Table 50. NFC Timing Parameters
+	 */
+	if (timings->tCLS_min > tRC_ps - 1000 ||
+	    timings->tCLH_min > tRC_ps - 2000 ||
+	    timings->tCS_min > tRC_ps - 1000 ||
+	    timings->tCH_min > tRC_ps - 2000 ||
+	    timings->tWP_min > tRC_ps - 1500 ||
+	    timings->tALS_min > tRC_ps ||
+	    timings->tALH_min > tRC_ps - 3000 ||
+	    timings->tDS_min > tRC_ps ||
+	    timings->tDH_min > tRC_ps - 5000 ||
+	    timings->tWC_min > 2 * tRC_ps ||
+	    timings->tWH_min > tRC_ps - 2500 ||
+	    timings->tRR_min > 6 * tRC_ps ||
+	    timings->tRP_min > 3 * tRC_ps / 2 ||
+	    timings->tRC_min > 2 * tRC_ps ||
+	    timings->tREH_min > (tRC_ps / 2) - 2500) {
+		dev_dbg(host->dev, "Timing out of bounds\n");
+		return -EINVAL;
+	}
+
+	if (check_only)
+		return 0;
+
+	ret = clk_set_rate(host->clk, rate);
+	if (ret)
+		return ret;
+
+	writew(config1, NFC_V1_V2_CONFIG1);
+
+	dev_dbg(host->dev, "Setting rate to %ldHz, %s mode\n", rate_round,
+		config1 & NFC_V2_CONFIG1_ONE_CYCLE ? "One cycle (EDO)" :
+		"normal");
+
+	return 0;
+}
+
 static void preset_v2(struct mtd_info *mtd)
 {
 	struct nand_chip *nand_chip = mtd_to_nand(mtd);
@@ -1278,8 +1357,6 @@ static int mxc_nand_onfi_get_features(struct mtd_info *mtd,
 	      & ONFI_OPT_CMD_SET_GET_FEATURES))
 		return -EINVAL;
 
-	*(uint32_t *)host->main_area0 = 0xdeadbeef;
-
 	host->devtype_data->send_cmd(host, NAND_CMD_GET_FEATURES, false);
 	mxc_do_addr_cycle(mtd, addr, -1);
 	host->devtype_data->send_page(mtd, NFC_OUTPUT);
@@ -1380,6 +1457,7 @@ static const struct mxc_nand_devtype_data imx25_nand_devtype_data = {
 	.ooblayout = &mxc_v2_ooblayout_ops,
 	.select_chip = mxc_nand_select_chip_v2,
 	.correct_data = mxc_nand_correct_data_v2_v3,
+	.setup_data_interface = mxc_nand_v2_setup_data_interface,
 	.irqpending_quirk = 0,
 	.needs_ip = 0,
 	.regs_offset = 0x1e00,
@@ -1588,6 +1666,8 @@ static int mxcnd_probe(struct platform_device *pdev)
 	if (err < 0)
 		return err;
 
+	this->setup_data_interface = host->devtype_data->setup_data_interface;
+
 	if (host->devtype_data->needs_ip) {
 		res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 		host->regs_ip = devm_ioremap_resource(&pdev->dev, res);