[][drivers: spi: add support for dynamic calibration]
[Description]
Add support for dynamic calibration:
Provide a calibration template for all SPI devices, including SPI-flash.
We just need to implement (*cal_read) in your SPI drivers, and then we
can use this calibration flow.
SPI signal path is usually affected by many aspects, like flash socket
mounted or longer signal line length. So we need dynamic calibration
for SPI controllers and devices before we start using SPI devices.
[Release-log]
N/A
Change-Id: I94313f3d186d425e8d73218d582cd9489af917c5
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/6151750
diff --git a/target/linux/mediatek/patches-5.4/9014-drivers-spi-Add-support-for-dynamic-calibration.patch b/target/linux/mediatek/patches-5.4/9014-drivers-spi-Add-support-for-dynamic-calibration.patch
new file mode 100644
index 0000000..688f33f
--- /dev/null
+++ b/target/linux/mediatek/patches-5.4/9014-drivers-spi-Add-support-for-dynamic-calibration.patch
@@ -0,0 +1,243 @@
+From a84c53fce4ccd67c147dcbb2dcf4fdeceab05981 Mon Sep 17 00:00:00 2001
+From: "SkyLake.Huang" <skylake.huang@mediatek.com>
+Date: Thu, 23 Jun 2022 18:35:52 +0800
+Subject: [PATCH] drivers: spi: Add support for dynamic calibration
+
+Signed-off-by: SkyLake.Huang <skylake.huang@mediatek.com>
+---
+ drivers/spi/spi.c | 137 ++++++++++++++++++++++++++++++++++++++++
+ include/linux/spi/spi.h | 42 ++++++++++++
+ 2 files changed, 179 insertions(+)
+
+diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
+index e562735a3..d548036b1 100644
+--- a/drivers/spi/spi.c
++++ b/drivers/spi/spi.c
+@@ -1109,6 +1109,70 @@ static int spi_transfer_wait(struct spi_controller *ctlr,
+ return 0;
+ }
+
++int spi_do_calibration(struct spi_controller *ctlr, struct spi_device *spi,
++ int (*cal_read)(void *priv, u32 *addr, int addrlen, u8 *buf, int readlen), void *drv_priv)
++{
++ int datalen = ctlr->cal_rule->datalen;
++ int addrlen = ctlr->cal_rule->addrlen;
++ u8 *buf;
++ int ret;
++ int i;
++ struct list_head *cal_head, *listptr;
++ struct spi_cal_target *target;
++
++ /* Calculate calibration result */
++ int hit_val, total_hit, origin;
++ bool hit;
++
++ /* Make sure we can start calibration */
++ if(!ctlr->cal_target || !ctlr->cal_rule || !ctlr->append_caldata)
++ return 0;
++
++ buf = kzalloc(datalen * sizeof(u8), GFP_KERNEL);
++ if(!buf)
++ return -ENOMEM;
++
++ ret = ctlr->append_caldata(ctlr);
++ if (ret)
++ goto cal_end;
++
++ cal_head = ctlr->cal_target;
++ list_for_each(listptr, cal_head) {
++ target = list_entry(listptr, struct spi_cal_target, list);
++
++ hit = false;
++ hit_val = 0;
++ total_hit = 0;
++ origin = *target->cal_item;
++
++ for(i=target->cal_min; i<=target->cal_max; i+=target->step) {
++ *target->cal_item = i;
++ ret = (*cal_read)(drv_priv, ctlr->cal_rule->addr, addrlen, buf, datalen);
++ if(ret)
++ break;
++ dev_dbg(&spi->dev, "controller cal item value: 0x%x\n", i);
++ if(memcmp(ctlr->cal_rule->match_data, buf, datalen * sizeof(u8)) == 0) {
++ hit = true;
++ hit_val += i;
++ total_hit++;
++ dev_dbg(&spi->dev, "golden data matches data read!\n");
++ }
++ }
++ if(hit) {
++ *target->cal_item = DIV_ROUND_CLOSEST(hit_val, total_hit);
++ dev_info(&spi->dev, "calibration result: 0x%x", *target->cal_item);
++ } else {
++ *target->cal_item = origin;
++ dev_warn(&spi->dev, "calibration failed, fallback to default: 0x%x", origin);
++ }
++ }
++
++cal_end:
++ kfree(buf);
++ return ret? ret: 0;
++}
++EXPORT_SYMBOL_GPL(spi_do_calibration);
++
+ static void _spi_transfer_delay_ns(u32 ns)
+ {
+ if (!ns)
+@@ -1720,6 +1784,75 @@ void spi_flush_queue(struct spi_controller *ctlr)
+ /*-------------------------------------------------------------------------*/
+
+ #if defined(CONFIG_OF)
++static inline void alloc_cal_data(struct list_head **cal_target,
++ struct spi_cal_rule **cal_rule, bool enable)
++{
++ if(enable) {
++ *cal_target = kmalloc(sizeof(struct list_head), GFP_KERNEL);
++ INIT_LIST_HEAD(*cal_target);
++ *cal_rule = kmalloc(sizeof(struct spi_cal_rule), GFP_KERNEL);
++ } else {
++ kfree(*cal_target);
++ kfree(*cal_rule);
++ }
++}
++
++static int of_spi_parse_cal_dt(struct spi_controller *ctlr, struct spi_device *spi,
++ struct device_node *nc)
++{
++ u32 value;
++ int rc;
++ const char *cal_mode;
++
++ rc = of_property_read_bool(nc, "spi-cal-enable");
++ if (rc)
++ alloc_cal_data(&ctlr->cal_target, &ctlr->cal_rule, true);
++ else
++ return 0;
++
++ rc = of_property_read_string(nc, "spi-cal-mode", &cal_mode);
++ if(!rc) {
++ if(strcmp("read-data", cal_mode) == 0){
++ ctlr->cal_rule->mode = SPI_CAL_READ_DATA;
++ } else if(strcmp("read-pp", cal_mode) == 0) {
++ ctlr->cal_rule->mode = SPI_CAL_READ_PP;
++ return 0;
++ } else if(strcmp("read-sfdp", cal_mode) == 0){
++ ctlr->cal_rule->mode = SPI_CAL_READ_SFDP;
++ return 0;
++ }
++ } else
++ goto err;
++
++ ctlr->cal_rule->datalen = 0;
++ rc = of_property_read_u32(nc, "spi-cal-datalen", &value);
++ if(!rc && value > 0) {
++ ctlr->cal_rule->datalen = value;
++
++ ctlr->cal_rule->match_data = kzalloc(value * sizeof(u8), GFP_KERNEL);
++ rc = of_property_read_u8_array(nc, "spi-cal-data",
++ ctlr->cal_rule->match_data, value);
++ if(rc)
++ kfree(ctlr->cal_rule->match_data);
++ }
++
++ rc = of_property_read_u32(nc, "spi-cal-addrlen", &value);
++ if(!rc && value > 0) {
++ ctlr->cal_rule->addrlen = value;
++
++ ctlr->cal_rule->addr = kzalloc(value * sizeof(u32), GFP_KERNEL);
++ rc = of_property_read_u32_array(nc, "spi-cal-addr",
++ ctlr->cal_rule->addr, value);
++ if(rc)
++ kfree(ctlr->cal_rule->addr);
++ }
++ return 0;
++
++err:
++ alloc_cal_data(&ctlr->cal_target, &ctlr->cal_rule, false);
++ return 0;
++}
++
+ static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
+ struct device_node *nc)
+ {
+@@ -1841,6 +1974,10 @@ of_register_spi_device(struct spi_controller *ctlr, struct device_node *nc)
+ if (rc)
+ goto err_out;
+
++ rc = of_spi_parse_cal_dt(ctlr, spi, nc);
++ if (rc)
++ goto err_out;
++
+ /* Store a pointer to the node in the device structure */
+ of_node_get(nc);
+ spi->dev.of_node = nc;
+diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
+index 7067f85ce..5330cd9b0 100644
+--- a/include/linux/spi/spi.h
++++ b/include/linux/spi/spi.h
+@@ -264,6 +264,40 @@ struct spi_driver {
+ struct device_driver driver;
+ };
+
++enum {
++ SPI_CAL_READ_DATA = 0,
++ SPI_CAL_READ_PP = 1, /* only for SPI-NAND */
++ SPI_CAL_READ_SFDP = 2, /* only for SPI-NOR */
++};
++
++struct nand_addr {
++ unsigned int lun;
++ unsigned int plane;
++ unsigned int eraseblock;
++ unsigned int page;
++ unsigned int dataoffs;
++};
++
++/**
++ * Read calibration rule from device dts node.
++ * Once calibration result matches the rule, we regard is as success.
++ */
++struct spi_cal_rule {
++ int datalen;
++ u8 *match_data;
++ int addrlen;
++ u32 *addr;
++ int mode;
++};
++
++struct spi_cal_target {
++ u32 *cal_item;
++ int cal_min; /* min of cal_item */
++ int cal_max; /* max of cal_item */
++ int step; /* Increase/decrease cal_item */
++ struct list_head list;
++};
++
+ static inline struct spi_driver *to_spi_driver(struct device_driver *drv)
+ {
+ return drv ? container_of(drv, struct spi_driver, driver) : NULL;
+@@ -606,6 +640,11 @@ struct spi_controller {
+ void *dummy_rx;
+ void *dummy_tx;
+
++ /* For calibration */
++ int (*append_caldata)(struct spi_controller *ctlr);
++ struct list_head *cal_target;
++ struct spi_cal_rule *cal_rule;
++
+ int (*fw_translate_cs)(struct spi_controller *ctlr, unsigned cs);
+ };
+
+@@ -1369,6 +1408,9 @@ spi_register_board_info(struct spi_board_info const *info, unsigned n)
+ { return 0; }
+ #endif
+
++extern int spi_do_calibration(struct spi_controller *ctlr,
++ struct spi_device *spi, int (*cal_read)(void *, u32 *, int, u8 *, int), void *drv_priv);
++
+ /* If you're hotplugging an adapter with devices (parport, usb, etc)
+ * use spi_new_device() to describe each device. You can also call
+ * spi_unregister_device() to start making that device vanish, but
+--
+2.18.0
+