Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Received-SPF: Pass (protection.outlook.com: domain of amd.com designates
 165.204.84.17 as permitted sender) receiver=protection.outlook.com;
 client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; pr=C
From:   Brad Larson <blarson@amd.com>
To:     <linux-arm-kernel@lists.infradead.org>
CC:     <linux-kernel@vger.kernel.org>, <linux-mmc@vger.kernel.org>,
        <linux-spi@vger.kernel.org>, <adrian.hunter@intel.com>,
        <alcooperx@gmail.com>, <andy.shevchenko@gmail.com>,
        <arnd@arndb.de>, <brad@pensando.io>, <blarson@amd.com>,
        <brendan.higgins@linux.dev>, <briannorris@chromium.org>,
        <brijeshkumar.singh@amd.com>, <catalin.marinas@arm.com>,
        <davidgow@google.com>, <gsomlo@gmail.com>, <gerg@linux-m68k.org>,
        <krzk@kernel.org>, <krzysztof.kozlowski+dt@linaro.org>,
        <lee@kernel.org>, <lee.jones@linaro.org>, <broonie@kernel.org>,
        <yamada.masahiro@socionext.com>, <p.zabel@pengutronix.de>,
        <piotrs@cadence.com>, <p.yadav@ti.com>, <rdunlap@infradead.org>,
        <robh+dt@kernel.org>, <samuel@sholland.org>,
        <fancer.lancer@gmail.com>, <skhan@linuxfoundation.org>,
        <suravee.suthikulpanit@amd.com>, <thomas.lendacky@amd.com>,
        <tonyhuang.sunplus@gmail.com>, <ulf.hansson@linaro.org>,
        <vaishnav.a@ti.com>, <will@kernel.org>,
        <devicetree@vger.kernel.org>
Subject: [PATCH v9 11/15] spi: dw: Add support for AMD Pensando Elba SoC
Date:   Wed, 18 Jan 2023 19:51:32 -0800
Message-ID: <20230119035136.21603-12-blarson@amd.com>
In-Reply-To: <20230119035136.21603-1-blarson@amd.com>
References: <20230119035136.21603-1-blarson@amd.com>
MIME-Version: 1.0
Content-Type: text/plain
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Jan 2023 03:52:56.2218
 (UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: cf8082cd-80d4-4fdc-2983-08daf9d0a639
X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d
X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com]
X-MS-Exchange-CrossTenant-AuthSource: CO1NAM11FT027.eop-nam11.prod.protection.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Anonymous
X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem
X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR12MB6918
X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE,
        RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_PASS autolearn=ham
        autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

The AMD Pensando Elba SoC includes a DW apb_ssi v4 controller
with device specific chip-select control.  The Elba SoC
provides four chip-selects where the native DW IP supports
two chip-selects.  The Elba DW_SPI instance has two native
CS signals that are always overridden.

Signed-off-by: Brad Larson <blarson@amd.com>
---

Changes since v6:
- Add use of macros GENMASK() and BIT()
- Change ELBA_SPICS_SHIFT() to ELBA_SPICS_OFFSET()

---
 drivers/spi/spi-dw-mmio.c | 78 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)

diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
index 26c40ea6dd12..9b6f876227e8 100644
--- a/drivers/spi/spi-dw-mmio.c
+++ b/drivers/spi/spi-dw-mmio.c
@@ -53,6 +53,24 @@ struct dw_spi_mscc {
 	void __iomem        *spi_mst; /* Not sparx5 */
 };
 
+struct dw_spi_elba {
+	struct regmap *syscon;
+};
+
+/*
+ * Elba SoC does not use ssi, pin override is used for cs 0,1 and
+ * gpios for cs 2,3 as defined in the device tree.
+ *
+ * cs:  |       1               0
+ * bit: |---3-------2-------1-------0
+ *      |  cs1   cs1_ovr   cs0   cs0_ovr
+ */
+#define ELBA_SPICS_REG			0x2468
+#define ELBA_SPICS_OFFSET(cs)		((cs) << 1)
+#define ELBA_SPICS_MASK(cs)		(GENMASK(1, 0) << ELBA_SPICS_OFFSET(cs))
+#define ELBA_SPICS_SET(cs, val)		\
+		((((val) << 1) | BIT(0)) << ELBA_SPICS_OFFSET(cs))
+
 /*
  * The Designware SPI controller (referred to as master in the documentation)
  * automatically deasserts chip select when the tx fifo is empty. The chip
@@ -237,6 +255,65 @@ static int dw_spi_canaan_k210_init(struct platform_device *pdev,
 	return 0;
 }
 
+static void dw_spi_elba_override_cs(struct dw_spi_elba *dwselba, int cs, int enable)
+{
+	regmap_update_bits(dwselba->syscon, ELBA_SPICS_REG, ELBA_SPICS_MASK(cs),
+			   ELBA_SPICS_SET(cs, enable));
+
+}
+
+static void dw_spi_elba_set_cs(struct spi_device *spi, bool enable)
+{
+	struct dw_spi *dws = spi_master_get_devdata(spi->master);
+	struct dw_spi_mmio *dwsmmio = container_of(dws, struct dw_spi_mmio, dws);
+	struct dw_spi_elba *dwselba = dwsmmio->priv;
+	u8 cs;
+
+	cs = spi->chip_select;
+	if (cs < 2)
+		dw_spi_elba_override_cs(dwselba, spi->chip_select, enable);
+
+	/*
+	 * The DW SPI controller needs a native CS bit selected to start
+	 * the serial engine.
+	 */
+	spi->chip_select = 0;
+	dw_spi_set_cs(spi, enable);
+	spi->chip_select = cs;
+}
+
+static int dw_spi_elba_init(struct platform_device *pdev,
+			    struct dw_spi_mmio *dwsmmio)
+{
+	const char *syscon_name = "amd,pensando-elba-syscon";
+	struct device_node *np = pdev->dev.of_node;
+	struct dw_spi_elba *dwselba;
+	struct device_node *node;
+	struct regmap *regmap;
+
+	node = of_parse_phandle(np, syscon_name, 0);
+	if (!node) {
+		dev_err(&pdev->dev, "failed to find %s\n", syscon_name);
+		return -ENODEV;
+	}
+
+	regmap = syscon_node_to_regmap(node);
+	if (IS_ERR(regmap)) {
+		dev_err(&pdev->dev, "syscon regmap lookup failed\n");
+		return PTR_ERR(regmap);
+	}
+
+	dwselba = devm_kzalloc(&pdev->dev, sizeof(*dwselba), GFP_KERNEL);
+	if (!dwselba)
+		return -ENOMEM;
+
+	dwselba->syscon = regmap;
+	dwsmmio->priv = dwselba;
+	dwsmmio->dws.set_cs = dw_spi_elba_set_cs;
+
+	return 0;
+}
+
 static int dw_spi_mmio_probe(struct platform_device *pdev)
 {
 	int (*init_func)(struct platform_device *pdev,
@@ -352,6 +429,7 @@ static const struct of_device_id dw_spi_mmio_of_match[] = {
 	{ .compatible = "intel,thunderbay-ssi", .data = dw_spi_intel_init},
 	{ .compatible = "microchip,sparx5-spi", dw_spi_mscc_sparx5_init},
 	{ .compatible = "canaan,k210-spi", dw_spi_canaan_k210_init},
+	{ .compatible = "amd,pensando-elba-spi", .data = dw_spi_elba_init},
 	{ /* end of table */}
 };
 MODULE_DEVICE_TABLE(of, dw_spi_mmio_of_match);
-- 
2.17.1