spi: mediatek: mt8173 spi multiple devices support

mt8173 IC spi HW has 4 gpio group, it's possible to support
max <= 4 slave devices, even mtk spi HW is not congruent to spi core.
1. When a device do a spi_message transfer, spi HW should know
   which pad-group this device is on, and then writes pad-select
   register.
2. Mtk pad-select register just selects which MISO pin HW will
   receive data. For example, pad-select=1(select spi1 pins), HW just
   receives data from spi1 MISO, but it still send waveform to all 4
   group cs/clk/mosi. If cs pin in other groups is still spi mode,
   after spi1 is selected(by active cs pin), devices on other group
   will also be selected.

Signed-off-by: Leilk Liu <leilk.liu@mediatek.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 52 insertions, 13 deletions

diff --git a/drivers/spi/spi-mt65xx.c b/drivers/spi/spi-mt65xx.c
index 406695a42e19..563954a61424 100644
--- a/drivers/spi/spi-mt65xx.c
+++ b/drivers/spi/spi-mt65xx.c
@@ -20,6 +20,7 @@
 #include <linux/ioport.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_gpio.h>
 #include <linux/platform_device.h>
 #include <linux/platform_data/spi-mt65xx.h>
 #include <linux/pm_runtime.h>
@@ -84,7 +85,8 @@ struct mtk_spi_compatible {
 struct mtk_spi {
         void __iomem *base;
         u32 state;
-        u32 pad_sel;
+        int pad_num;
+        u32 *pad_sel;
         struct clk *parent_clk, *sel_clk, *spi_clk;
         struct spi_transfer *cur_transfer;
         u32 xfer_len;
@@ -188,7 +190,8 @@ static int mtk_spi_prepare_message(struct spi_master *master,
 
         /* pad select */
         if (mdata->dev_comp->need_pad_sel)
-                writel(mdata->pad_sel, mdata->base + SPI_PAD_SEL_REG);
+                writel(mdata->pad_sel[spi->chip_select],
+                       mdata->base + SPI_PAD_SEL_REG);
 
         return 0;
 }
@@ -407,6 +410,9 @@ static int mtk_spi_setup(struct spi_device *spi)
         if (!spi->controller_data)
                 spi->controller_data = (void *)&mtk_default_chip_info;
 
+        if (mdata->dev_comp->need_pad_sel)
+                gpio_direction_output(spi->cs_gpio, !(spi->mode & SPI_CS_HIGH));
+
         return 0;
 }
 
@@ -481,7 +487,7 @@ static int mtk_spi_probe(struct platform_device *pdev)
         struct mtk_spi *mdata;
         const struct of_device_id *of_id;
         struct resource *res;
-        int irq, ret;
+        int i, irq, ret;
 
         master = spi_alloc_master(&pdev->dev, sizeof(*mdata));
         if (!master) {
@@ -512,21 +518,34 @@ static int mtk_spi_probe(struct platform_device *pdev)
                 master->flags = SPI_MASTER_MUST_TX;
 
         if (mdata->dev_comp->need_pad_sel) {
-                ret = of_property_read_u32(pdev->dev.of_node,
-                                           "mediatek,pad-select",
-                                           &mdata->pad_sel);
-                if (ret) {
-                        dev_err(&pdev->dev, "failed to read pad select: %d\n",
-                                ret);
+                mdata->pad_num = of_property_count_u32_elems(
+                        pdev->dev.of_node,
+                        "mediatek,pad-select");
+                if (mdata->pad_num < 0) {
+                        dev_err(&pdev->dev,
+                                "No 'mediatek,pad-select' property\n");
+                        ret = -EINVAL;
                         goto err_put_master;
                 }
 
-                if (mdata->pad_sel > MT8173_SPI_MAX_PAD_SEL) {
-                        dev_err(&pdev->dev, "wrong pad-select: %u\n",
-                                mdata->pad_sel);
-                        ret = -EINVAL;
+                mdata->pad_sel = devm_kmalloc_array(&pdev->dev, mdata->pad_num,
+                                                    sizeof(u32), GFP_KERNEL);
+                if (!mdata->pad_sel) {
+                        ret = -ENOMEM;
                         goto err_put_master;
                 }
+
+                for (i = 0; i < mdata->pad_num; i++) {
+                        of_property_read_u32_index(pdev->dev.of_node,
+                                                   "mediatek,pad-select",
+                                                   i, &mdata->pad_sel[i]);
+                        if (mdata->pad_sel[i] > MT8173_SPI_MAX_PAD_SEL) {
+                                dev_err(&pdev->dev, "wrong pad-sel[%d]: %u\n",
+                                        i, mdata->pad_sel[i]);
+                                ret = -EINVAL;
+                                goto err_put_master;
+                        }
+                }
         }
 
         platform_set_drvdata(pdev, master);
@@ -604,6 +623,26 @@ static int mtk_spi_probe(struct platform_device *pdev)
                 goto err_put_master;
         }
 
+        if (mdata->dev_comp->need_pad_sel) {
+                if (mdata->pad_num != master->num_chipselect) {
+                        dev_err(&pdev->dev,
+                                "pad_num does not match num_chipselect(%d != %d)\n",
+                                mdata->pad_num, master->num_chipselect);
+                        ret = -EINVAL;
+                        goto err_put_master;
+                }
+
+                for (i = 0; i < master->num_chipselect; i++) {
+                        ret = devm_gpio_request(&pdev->dev, master->cs_gpios[i],
+                                                dev_name(&pdev->dev));
+                        if (ret) {
+                                dev_err(&pdev->dev,
+                                        "can't get CS GPIO %i\n", i);
+                                goto err_put_master;
+                        }
+                }
+        }
+
         return 0;
 
 err_disable_clk: