[PATCHv6 4/6] mmc: dw_mmc-pltfm: socfpga: add method to configure clk-phase

[Dinh Nguyen <dinguyen@xxxxxxxxxx>]

The clock-phase settings for the SDMMC controller in the SoCFPGA
platforms reside in a register in the System Manager. Add a method
to access that register through the syscon interface.

Signed-off-by: Dinh Nguyen <dinguyen@xxxxxxxxxx>
---
v6: not getting the clk-phase-sd-hs is not a hard failure
v5: change error handling from of_property_read_variable_u32_array()
    support arm32 by reading the reg_shift
v4: no change
v3: add space before &socfpga_drv_data
v2: simplify clk-phase calculations

make property optional in driver
---
 drivers/mmc/host/dw_mmc-pltfm.c | 43 ++++++++++++++++++++++++++++++++-
 1 file changed, 42 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/dw_mmc-pltfm.c b/drivers/mmc/host/dw_mmc-pltfm.c
index 9901208be797..fff6222d58e4 100644
--- a/drivers/mmc/host/dw_mmc-pltfm.c
+++ b/drivers/mmc/host/dw_mmc-pltfm.c
@@ -17,10 +17,16 @@
 #include <linux/mmc/host.h>
 #include <linux/mmc/mmc.h>
 #include <linux/of.h>
+#include <linux/mfd/altera-sysmgr.h>
+#include <linux/regmap.h>
 
 #include "dw_mmc.h"
 #include "dw_mmc-pltfm.h"
 
+#define SOCFPGA_DW_MMC_CLK_PHASE_STEP	45
+#define SYSMGR_SDMMC_CTRL_SET(smplsel, drvsel, reg_shift) \
+	((((smplsel) & 0x7) << reg_shift) | (((drvsel) & 0x7) << 0))
+
 int dw_mci_pltfm_register(struct platform_device *pdev,
 			  const struct dw_mci_drv_data *drv_data)
 {
@@ -62,9 +68,44 @@ const struct dev_pm_ops dw_mci_pltfm_pmops = {
 };
 EXPORT_SYMBOL_GPL(dw_mci_pltfm_pmops);
 
+static int dw_mci_socfpga_priv_init(struct dw_mci *host)
+{
+	struct device_node *np = host->dev->of_node;
+	struct regmap *sys_mgr_base_addr;
+	u32 clk_phase[2] = {0}, reg_offset, reg_shift;
+	int i, rc, hs_timing;
+
+	rc = of_property_read_variable_u32_array(np, "clk-phase-sd-hs", &clk_phase[0], 2, 0);
+	if (rc < 0) {
+		dev_info(host->dev, "Optional: clk-phase-sd-hs not found!\n");
+		return 0;
+	}
+
+	sys_mgr_base_addr = altr_sysmgr_regmap_lookup_by_phandle(np, "altr,sysmgr-syscon");
+	if (IS_ERR(sys_mgr_base_addr)) {
+		dev_info(host->dev, "Optional: failed to find altr,sys-mgr regmap!\n");
+		return 0;
+	}
+
+	of_property_read_u32_index(np, "altr,sysmgr-syscon", 1, &reg_offset);
+	of_property_read_u32_index(np, "altr,sysmgr-syscon", 2, &reg_shift);
+
+	for (i = 0; i < ARRAY_SIZE(clk_phase); i++)
+		clk_phase[i] /= SOCFPGA_DW_MMC_CLK_PHASE_STEP;
+
+	hs_timing = SYSMGR_SDMMC_CTRL_SET(clk_phase[0], clk_phase[1], reg_shift);
+	regmap_write(sys_mgr_base_addr, reg_offset, hs_timing);
+
+	return 0;
+}
+
+static const struct dw_mci_drv_data socfpga_drv_data = {
+	.init		= dw_mci_socfpga_priv_init,
+};
+
 static const struct of_device_id dw_mci_pltfm_match[] = {
 	{ .compatible = "snps,dw-mshc", },
-	{ .compatible = "altr,socfpga-dw-mshc", },
+	{ .compatible = "altr,socfpga-dw-mshc", .data = &socfpga_drv_data, },
 	{ .compatible = "img,pistachio-dw-mshc", },
 	{},
 };
-- 
2.25.1