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author | Álvaro Fernández Rojas <noltari@gmail.com> | 2019-12-23 13:42:55 +0100 |
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committer | Álvaro Fernández Rojas <noltari@gmail.com> | 2019-12-24 18:49:44 +0100 |
commit | 67dcc43f3a22dc3a7ac07a7065971b426feeb043 (patch) | |
tree | 0b647356dce45d2c79fd46cf201daa5089cc0934 /target/linux/brcm2708/patches-4.19/950-0470-i2c-bcm2835-Model-Divider-in-CCF.patch | |
parent | 47a93a810f78adce5a130d287f82b28e9b54313c (diff) | |
download | upstream-67dcc43f3a22dc3a7ac07a7065971b426feeb043.tar.gz upstream-67dcc43f3a22dc3a7ac07a7065971b426feeb043.tar.bz2 upstream-67dcc43f3a22dc3a7ac07a7065971b426feeb043.zip |
brcm2708: organize kernel patches
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Diffstat (limited to 'target/linux/brcm2708/patches-4.19/950-0470-i2c-bcm2835-Model-Divider-in-CCF.patch')
-rw-r--r-- | target/linux/brcm2708/patches-4.19/950-0470-i2c-bcm2835-Model-Divider-in-CCF.patch | 270 |
1 files changed, 270 insertions, 0 deletions
diff --git a/target/linux/brcm2708/patches-4.19/950-0470-i2c-bcm2835-Model-Divider-in-CCF.patch b/target/linux/brcm2708/patches-4.19/950-0470-i2c-bcm2835-Model-Divider-in-CCF.patch new file mode 100644 index 0000000000..dc251a60c4 --- /dev/null +++ b/target/linux/brcm2708/patches-4.19/950-0470-i2c-bcm2835-Model-Divider-in-CCF.patch @@ -0,0 +1,270 @@ +From ffbb6cc14b8fb1876b249048284a5fe30f48c693 Mon Sep 17 00:00:00 2001 +From: Annaliese McDermond <nh6z@nh6z.net> +Date: Sat, 8 Jun 2019 10:14:43 -0700 +Subject: [PATCH] i2c: bcm2835: Model Divider in CCF + +Commit bebff81fb8b9216eb4fba22cf910553621ae3477 upstream. + +Model the I2C bus clock divider as a part of the Core Clock Framework. +Primarily this removes the clk_get_rate() call from each transfer. +This call causes problems for slave drivers that themselves have +internal clock components that are controlled by an I2C interface. +When the slave's internal clock component is prepared, the prepare +lock is obtained, and it makes calls to the I2C subsystem to +command the hardware to activate the clock. In order to perform +the I2C transfer, this driver sets the divider, which requires +it to get the parent clock rate, which it does with clk_get_rate(). +Unfortunately, this function will try to take the clock prepare +lock, which is already held by the slave's internal clock calls +creating a deadlock. + +Modeling the divider in the CCF natively removes this dependency +and the divider value is only set upon changing the bus clock +frequency or changes in the parent clock that cascade down to this +divisor. This obviates the need to set the divider with every +transfer and avoids the deadlock described above. It also should +provide better clock debugging and save a few cycles on each +transfer due to not having to recalcuate the divider value. + +Signed-off-by: Annaliese McDermond <nh6z@nh6z.net> +Acked-by: Stefan Wahren <stefan.wahren@i2se.com> +Reviewed-by: Eric Anholt <eric@anholt.net> +Signed-off-by: Wolfram Sang <wsa@the-dreams.de> +--- + drivers/i2c/busses/i2c-bcm2835.c | 145 ++++++++++++++++++++++++------- + 1 file changed, 114 insertions(+), 31 deletions(-) + +--- a/drivers/i2c/busses/i2c-bcm2835.c ++++ b/drivers/i2c/busses/i2c-bcm2835.c +@@ -12,6 +12,8 @@ + */ + + #include <linux/clk.h> ++#include <linux/clkdev.h> ++#include <linux/clk-provider.h> + #include <linux/completion.h> + #include <linux/err.h> + #include <linux/i2c.h> +@@ -71,9 +73,7 @@ struct bcm2835_debug { + struct bcm2835_i2c_dev { + struct device *dev; + void __iomem *regs; +- struct clk *clk; + int irq; +- u32 bus_clk_rate; + struct i2c_adapter adapter; + struct completion completion; + struct i2c_msg *curr_msg; +@@ -164,12 +164,17 @@ static inline u32 bcm2835_i2c_readl(stru + return readl(i2c_dev->regs + reg); + } + +-static int bcm2835_i2c_set_divider(struct bcm2835_i2c_dev *i2c_dev) ++#define to_clk_bcm2835_i2c(_hw) container_of(_hw, struct clk_bcm2835_i2c, hw) ++struct clk_bcm2835_i2c { ++ struct clk_hw hw; ++ struct bcm2835_i2c_dev *i2c_dev; ++}; ++ ++static int clk_bcm2835_i2c_calc_divider(unsigned long rate, ++ unsigned long parent_rate) + { +- u32 divider, redl, fedl; ++ u32 divider = DIV_ROUND_UP(parent_rate, rate); + +- divider = DIV_ROUND_UP(clk_get_rate(i2c_dev->clk), +- i2c_dev->bus_clk_rate); + /* + * Per the datasheet, the register is always interpreted as an even + * number, by rounding down. In other words, the LSB is ignored. So, +@@ -178,12 +183,23 @@ static int bcm2835_i2c_set_divider(struc + if (divider & 1) + divider++; + if ((divider < BCM2835_I2C_CDIV_MIN) || +- (divider > BCM2835_I2C_CDIV_MAX)) { +- dev_err_ratelimited(i2c_dev->dev, "Invalid clock-frequency\n"); ++ (divider > BCM2835_I2C_CDIV_MAX)) + return -EINVAL; +- } + +- bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DIV, divider); ++ return divider; ++} ++ ++static int clk_bcm2835_i2c_set_rate(struct clk_hw *hw, unsigned long rate, ++ unsigned long parent_rate) ++{ ++ struct clk_bcm2835_i2c *div = to_clk_bcm2835_i2c(hw); ++ u32 redl, fedl; ++ u32 divider = clk_bcm2835_i2c_calc_divider(rate, parent_rate); ++ ++ if (divider == -EINVAL) ++ return -EINVAL; ++ ++ bcm2835_i2c_writel(div->i2c_dev, BCM2835_I2C_DIV, divider); + + /* + * Number of core clocks to wait after falling edge before +@@ -198,12 +214,62 @@ static int bcm2835_i2c_set_divider(struc + */ + redl = max(divider / 4, 1u); + +- bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DEL, ++ bcm2835_i2c_writel(div->i2c_dev, BCM2835_I2C_DEL, + (fedl << BCM2835_I2C_FEDL_SHIFT) | + (redl << BCM2835_I2C_REDL_SHIFT)); + return 0; + } + ++static long clk_bcm2835_i2c_round_rate(struct clk_hw *hw, unsigned long rate, ++ unsigned long *parent_rate) ++{ ++ u32 divider = clk_bcm2835_i2c_calc_divider(rate, *parent_rate); ++ ++ return DIV_ROUND_UP(*parent_rate, divider); ++} ++ ++static unsigned long clk_bcm2835_i2c_recalc_rate(struct clk_hw *hw, ++ unsigned long parent_rate) ++{ ++ struct clk_bcm2835_i2c *div = to_clk_bcm2835_i2c(hw); ++ u32 divider = bcm2835_i2c_readl(div->i2c_dev, BCM2835_I2C_DIV); ++ ++ return DIV_ROUND_UP(parent_rate, divider); ++} ++ ++static const struct clk_ops clk_bcm2835_i2c_ops = { ++ .set_rate = clk_bcm2835_i2c_set_rate, ++ .round_rate = clk_bcm2835_i2c_round_rate, ++ .recalc_rate = clk_bcm2835_i2c_recalc_rate, ++}; ++ ++static struct clk *bcm2835_i2c_register_div(struct device *dev, ++ const char *mclk_name, ++ struct bcm2835_i2c_dev *i2c_dev) ++{ ++ struct clk_init_data init; ++ struct clk_bcm2835_i2c *priv; ++ char name[32]; ++ ++ snprintf(name, sizeof(name), "%s_div", dev_name(dev)); ++ ++ init.ops = &clk_bcm2835_i2c_ops; ++ init.name = name; ++ init.parent_names = (const char* []) { mclk_name }; ++ init.num_parents = 1; ++ init.flags = 0; ++ ++ priv = devm_kzalloc(dev, sizeof(struct clk_bcm2835_i2c), GFP_KERNEL); ++ if (priv == NULL) ++ return ERR_PTR(-ENOMEM); ++ ++ priv->hw.init = &init; ++ priv->i2c_dev = i2c_dev; ++ ++ clk_hw_register_clkdev(&priv->hw, "div", dev_name(dev)); ++ return devm_clk_register(dev, &priv->hw); ++} ++ + static void bcm2835_fill_txfifo(struct bcm2835_i2c_dev *i2c_dev) + { + u32 val; +@@ -363,7 +429,7 @@ static int bcm2835_i2c_xfer(struct i2c_a + { + struct bcm2835_i2c_dev *i2c_dev = i2c_get_adapdata(adap); + unsigned long time_left; +- int i, ret; ++ int i; + + if (debug) + i2c_dev->debug_num_msgs = num; +@@ -379,10 +445,6 @@ static int bcm2835_i2c_xfer(struct i2c_a + return -EOPNOTSUPP; + } + +- ret = bcm2835_i2c_set_divider(i2c_dev); +- if (ret) +- return ret; +- + i2c_dev->curr_msg = msgs; + i2c_dev->num_msgs = num; + reinit_completion(&i2c_dev->completion); +@@ -443,6 +505,9 @@ static int bcm2835_i2c_probe(struct plat + struct resource *mem, *irq; + int ret; + struct i2c_adapter *adap; ++ const char *mclk_name; ++ struct clk *bus_clk; ++ u32 bus_clk_rate; + + i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL); + if (!i2c_dev) +@@ -456,21 +521,6 @@ static int bcm2835_i2c_probe(struct plat + if (IS_ERR(i2c_dev->regs)) + return PTR_ERR(i2c_dev->regs); + +- i2c_dev->clk = devm_clk_get(&pdev->dev, NULL); +- if (IS_ERR(i2c_dev->clk)) { +- if (PTR_ERR(i2c_dev->clk) != -EPROBE_DEFER) +- dev_err(&pdev->dev, "Could not get clock\n"); +- return PTR_ERR(i2c_dev->clk); +- } +- +- ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency", +- &i2c_dev->bus_clk_rate); +- if (ret < 0) { +- dev_warn(&pdev->dev, +- "Could not read clock-frequency property\n"); +- i2c_dev->bus_clk_rate = 100000; +- } +- + irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0); + if (!irq) { + dev_err(&pdev->dev, "No IRQ resource\n"); +@@ -485,6 +535,35 @@ static int bcm2835_i2c_probe(struct plat + return -ENODEV; + } + ++ mclk_name = of_clk_get_parent_name(pdev->dev.of_node, 0); ++ ++ bus_clk = bcm2835_i2c_register_div(&pdev->dev, mclk_name, i2c_dev); ++ ++ if (IS_ERR(bus_clk)) { ++ dev_err(&pdev->dev, "Could not register clock\n"); ++ return PTR_ERR(bus_clk); ++ } ++ ++ ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency", ++ &bus_clk_rate); ++ if (ret < 0) { ++ dev_warn(&pdev->dev, ++ "Could not read clock-frequency property\n"); ++ bus_clk_rate = 100000; ++ } ++ ++ ret = clk_set_rate_exclusive(bus_clk, bus_clk_rate); ++ if (ret < 0) { ++ dev_err(&pdev->dev, "Could not set clock frequency\n"); ++ return ret; ++ } ++ ++ ret = clk_prepare_enable(bus_clk); ++ if (ret) { ++ dev_err(&pdev->dev, "Couldn't prepare clock"); ++ return ret; ++ } ++ + adap = &i2c_dev->adapter; + i2c_set_adapdata(adap, i2c_dev); + adap->owner = THIS_MODULE; +@@ -507,6 +586,10 @@ static int bcm2835_i2c_probe(struct plat + static int bcm2835_i2c_remove(struct platform_device *pdev) + { + struct bcm2835_i2c_dev *i2c_dev = platform_get_drvdata(pdev); ++ struct clk *bus_clk = devm_clk_get(i2c_dev->dev, "div"); ++ ++ clk_rate_exclusive_put(bus_clk); ++ clk_disable_unprepare(bus_clk); + + free_irq(i2c_dev->irq, i2c_dev); + i2c_del_adapter(&i2c_dev->adapter); |